diff --git a/backend/alembic/versions/339b78011a4f_add_user_text_scale_preference.py b/backend/alembic/versions/339b78011a4f_add_user_text_scale_preference.py
new file mode 100644
index 0000000..94c077e
--- /dev/null
+++ b/backend/alembic/versions/339b78011a4f_add_user_text_scale_preference.py
@@ -0,0 +1,32 @@
+"""add user text_scale preference
+
+Revision ID: 339b78011a4f
+Revises: a318850726ee
+Create Date: 2026-08-30 18:03:16.159924
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '339b78011a4f'
+down_revision: Union[str, Sequence[str], None] = 'a318850726ee'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('users', sa.Column('text_scale', sa.String(length=20), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('users', 'text_scale')
+    # ### end Alembic commands ###
diff --git a/backend/alembic/versions/e81c9bcc82b9_add_user_emoji_scale_preference.py b/backend/alembic/versions/e81c9bcc82b9_add_user_emoji_scale_preference.py
new file mode 100644
index 0000000..12311a1
--- /dev/null
+++ b/backend/alembic/versions/e81c9bcc82b9_add_user_emoji_scale_preference.py
@@ -0,0 +1,32 @@
+"""add user emoji_scale preference
+
+Revision ID: e81c9bcc82b9
+Revises: 339b78011a4f
+Create Date: 2026-08-30 18:14:26.045186
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'e81c9bcc82b9'
+down_revision: Union[str, Sequence[str], None] = '339b78011a4f'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('users', sa.Column('emoji_scale', sa.String(length=20), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('users', 'emoji_scale')
+    # ### end Alembic commands ###
diff --git a/backend/app/models/user.py b/backend/app/models/user.py
index 4a85958..d65b85e 100644
--- a/backend/app/models/user.py
+++ b/backend/app/models/user.py
@@ -19,6 +19,17 @@ class User(Base):
     is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
     display_name: Mapped[str | None] = mapped_column(String(50))
     theme: Mapped[str | None] = mapped_column(String(20))
+    # #71: null means "normal" (the pre-existing default before this
+    # setting existed) -- a preset name, not a raw scale factor, so it's
+    # validated/enumerable the same way `theme` already is rather than
+    # accepting an arbitrary float.
+    text_scale: Mapped[str | None] = mapped_column(String(20))
+    # #71: independent of text_scale above -- scales emoji rendered in
+    # message text specifically, not the whole UI (see
+    # frontend/src/components/MessageContent.tsx's --emoji-scale, scoped
+    # to message content only so it can't also inflate the emoji picker's
+    # grid or reaction pills).
+    emoji_scale: Mapped[str | None] = mapped_column(String(20))
     # Only meaningful when theme == "custom" -- which of this user's saved
     # CustomTheme rows (app/models/custom_theme.py) is currently active.
     # Cleared explicitly (not via a DB-level ON DELETE) whenever that theme
diff --git a/backend/app/routers/auth.py b/backend/app/routers/auth.py
index af16b08..3533ecd 100644
--- a/backend/app/routers/auth.py
+++ b/backend/app/routers/auth.py
@@ -100,6 +100,10 @@ async def update_profile(
         current_user.display_name = display_name or None
     if "theme" in updates:
         current_user.theme = updates["theme"]
+    if "text_scale" in updates:
+        current_user.text_scale = updates["text_scale"]
+    if "emoji_scale" in updates:
+        current_user.emoji_scale = updates["emoji_scale"]
     if "appear_offline" in updates:
         current_user.appear_offline = updates["appear_offline"]
     await db.commit()
diff --git a/backend/app/schemas/user.py b/backend/app/schemas/user.py
index f3acb32..481e278 100644
--- a/backend/app/schemas/user.py
+++ b/backend/app/schemas/user.py
@@ -23,6 +23,8 @@ class UserRead(BaseModel):
     is_site_admin: bool
     display_name: str | None
     theme: str | None
+    text_scale: str | None
+    emoji_scale: str | None
     # Resolved, not just an id -- the frontend needs the actual palette to
     # paint on load without a second round trip (see lib/theme.ts).
     active_custom_theme: CustomThemeRead | None
@@ -57,6 +59,10 @@ class ProfileUpdate(BaseModel):
     # ownership check; that's POST /api/custom-themes/{id}/activate, not a
     # bare theme name with nothing to point it at.
     theme: Literal["dark", "light", "midnight", "sunset"] | None = Field(default=None)
+    # #71: kept in sync with frontend/src/lib/theme.ts's TEXT_SCALE_PERCENT map.
+    text_scale: Literal["small", "normal", "large", "xlarge"] | None = Field(default=None)
+    # #71: kept in sync with MessageContent.tsx's EMOJI_SCALE_MULTIPLIER map.
+    emoji_scale: Literal["small", "normal", "large", "xlarge"] | None = Field(default=None)
     appear_offline: bool | None = Field(default=None)
 
 
diff --git a/backend/tests/test_profile.py b/backend/tests/test_profile.py
index 1647d02..6f611d1 100644
--- a/backend/tests/test_profile.py
+++ b/backend/tests/test_profile.py
@@ -102,6 +102,62 @@ async def test_theme_custom_rejected_on_generic_profile_update(client, db_sessio
     assert resp.status_code == 422
 
 
+async def test_update_text_scale_persists(client, db_session):
+    await register_and_login(client, db_session, username=_unique("alice"))
+
+    resp = await client.patch("/api/auth/me", json={"text_scale": "large"})
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["text_scale"] == "large"
+
+    me = await client.get("/api/auth/me")
+    assert me.json()["text_scale"] == "large"
+
+
+async def test_invalid_text_scale_rejected(client, db_session):
+    await register_and_login(client, db_session, username=_unique("alice"))
+
+    resp = await client.patch("/api/auth/me", json={"text_scale": "huge"})
+    assert resp.status_code == 422
+
+
+async def test_updating_text_scale_does_not_clobber_theme(client, db_session):
+    await register_and_login(client, db_session, username=_unique("alice"))
+    await client.patch("/api/auth/me", json={"theme": "sunset"})
+
+    resp = await client.patch("/api/auth/me", json={"text_scale": "xlarge"})
+    assert resp.status_code == 200
+    assert resp.json()["theme"] == "sunset"
+    assert resp.json()["text_scale"] == "xlarge"
+
+
+async def test_update_emoji_scale_persists(client, db_session):
+    await register_and_login(client, db_session, username=_unique("alice"))
+
+    resp = await client.patch("/api/auth/me", json={"emoji_scale": "xlarge"})
+    assert resp.status_code == 200, resp.text
+    assert resp.json()["emoji_scale"] == "xlarge"
+
+    me = await client.get("/api/auth/me")
+    assert me.json()["emoji_scale"] == "xlarge"
+
+
+async def test_invalid_emoji_scale_rejected(client, db_session):
+    await register_and_login(client, db_session, username=_unique("alice"))
+
+    resp = await client.patch("/api/auth/me", json={"emoji_scale": "huge"})
+    assert resp.status_code == 422
+
+
+async def test_updating_emoji_scale_does_not_clobber_text_scale(client, db_session):
+    await register_and_login(client, db_session, username=_unique("alice"))
+    await client.patch("/api/auth/me", json={"text_scale": "large"})
+
+    resp = await client.patch("/api/auth/me", json={"emoji_scale": "small"})
+    assert resp.status_code == 200
+    assert resp.json()["text_scale"] == "large"
+    assert resp.json()["emoji_scale"] == "small"
+
+
 async def test_avatar_upload_succeeds_and_persists(client, db_session):
     await register_and_login(client, db_session, username=_unique("alice"))
 
diff --git a/frontend/src/api/auth.ts b/frontend/src/api/auth.ts
index a195473..2d679b3 100644
--- a/frontend/src/api/auth.ts
+++ b/frontend/src/api/auth.ts
@@ -1,5 +1,5 @@
 import { apiFetch, ApiError, NetworkError } from './client'
-import type { User, UserSession } from '../types'
+import type { EmojiScale, TextScale, User, UserSession } from '../types'
 
 // No register() here: this is an invite-only site. Accounts are created by
 // an operator via the backend CLI (`python -m app.cli create-user`), not
@@ -50,6 +50,23 @@ export function updateTheme(theme: 'dark' | 'light' | 'midnight' | 'sunset'): Pr
   })
 }
 
+// #71: its own call, same reasoning as updateTheme above -- the backend
+// only applies fields actually present in the request body, so this can't
+// clobber theme (or vice versa).
+export function updateTextScale(textScale: TextScale): Promise<User> {
+  return apiFetch<User>('/api/auth/me', {
+    method: 'PATCH',
+    body: JSON.stringify({ text_scale: textScale }),
+  })
+}
+
+export function updateEmojiScale(emojiScale: EmojiScale): Promise<User> {
+  return apiFetch<User>('/api/auth/me', {
+    method: 'PATCH',
+    body: JSON.stringify({ emoji_scale: emojiScale }),
+  })
+}
+
 export function removeAvatar(): Promise<User> {
   return apiFetch<User>('/api/auth/me/avatar', { method: 'DELETE' })
 }
diff --git a/frontend/src/components/MessageContent.css b/frontend/src/components/MessageContent.css
index 2a806fb..98bc3aa 100644
--- a/frontend/src/components/MessageContent.css
+++ b/frontend/src/components/MessageContent.css
@@ -4,10 +4,38 @@
    own font-size and this just tracks it. Kept in this file (imported
    directly by MessageContent.tsx) rather than MessageList.css so it's
    loaded wherever MessageContent renders -- FilePreviewModal and HelpPage
-   included, not just the message list. */
+   included, not just the message list.
+
+   #71: also multiplied by --emoji-scale, the manual "make emoji bigger"
+   preference -- but that variable is only ever set on MessageContent's own
+   wrapper div (inline style, scoped to that element and its descendants),
+   never at :root, so var(..., 1) correctly falls back to a no-op multiplier
+   everywhere else this class is reused (the picker's grid, reaction pills)
+   instead of also inflating those and breaking their fixed-size layout. */
 .message-custom-emoji {
-  height: 1.2em;
-  width: 1.2em;
+  height: calc(1.2em * var(--emoji-scale, 1));
+  width: calc(1.2em * var(--emoji-scale, 1));
   object-fit: contain;
   vertical-align: -0.25em;
 }
+
+/* #71: a raw unicode emoji wrapped by wrapEmojiGlyphs -- same --emoji-scale
+   multiplier as the custom-emoji image above, so "make emoji bigger"
+   applies uniformly regardless of which kind of emoji it is. */
+.inline-emoji {
+  display: inline-block;
+  font-size: calc(1em * var(--emoji-scale, 1));
+}
+
+/* #71: Discord/Slack-style large rendering for a message that's nothing
+   but emoji (see isEmojiOnlyMessage) -- em-relative like everything else
+   here, so it scales on top of the text-size setting rather than
+   overriding it, and also honors --emoji-scale on top of its own 2.5x (a
+   message that's only emoji AND has "Extra large" emoji picked should be
+   bigger still, not capped at a fixed size regardless of that setting).
+   .message-custom-emoji's own em-sizing means a custom emoji picks this up
+   for free, no separate rule needed. */
+.message-text-emoji-only {
+  font-size: calc(2.5em * var(--emoji-scale, 1));
+  line-height: 1.2;
+}
diff --git a/frontend/src/components/MessageContent.tsx b/frontend/src/components/MessageContent.tsx
index 0531401..7236b0a 100644
--- a/frontend/src/components/MessageContent.tsx
+++ b/frontend/src/components/MessageContent.tsx
@@ -1,7 +1,8 @@
 import Markdown from 'markdown-to-jsx'
-import type { ReactNode } from 'react'
+import type { CSSProperties, ReactNode } from 'react'
 import { Link } from 'react-router-dom'
 import { getCustomEmojiUrl } from '../api/customEmoji'
+import { useAuth } from '../context/AuthContext'
 import { useCustomEmoji } from '../context/CustomEmojiContext'
 import { EMOJI_SHORTCODES } from '../lib/emojiShortcodes'
 import './MessageContent.css'
@@ -85,6 +86,14 @@ function MarkdownLink({ href, children }: MarkdownLinkProps) {
       />
     )
   }
+  // #71: a raw unicode emoji has no element of its own to size independently
+  // of the surrounding text -- it's just characters in a string. Wrapping
+  // each one individually (see wrapEmojiGlyphs below) gives it one, purely
+  // so the emoji-size preference can scale it via CSS the same way it
+  // already scales a custom emoji's <img>.
+  if (href === 'glyph:') {
+    return <span className="inline-emoji">{children}</span>
+  }
   return (
     <a href={href} target="_blank" rel="noopener noreferrer">
       {children}
@@ -247,7 +256,12 @@ export function EmojiGlyph({ value }: EmojiGlyphProps) {
       />
     )
   }
-  return <>{value}</>
+  // Wrapped the same way wrapEmojiGlyphs wraps a raw emoji in message text
+  // (see .inline-emoji), so a --emoji-scale set on an ancestor (the
+  // reaction pill's own span in MessageList.tsx) scales this the same way
+  // it scales the .message-custom-emoji img above -- and falls back to a
+  // no-op 1x everywhere else (the picker) with no --emoji-scale set at all.
+  return <span className="inline-emoji">{value}</span>
 }
 
 const MENTION_PATTERN = /@([a-zA-Z0-9_.-]+)/g
@@ -370,14 +384,98 @@ export function preprocessMarkdown(text: string): { text: string; headingIds: Ma
   return extractHeadingIds(convertSubSuperscript(text))
 }
 
+// #71: Discord/Slack-style -- a message that's *nothing but* emoji renders
+// them noticeably larger, no manual control needed. `\p{Extended_Pictographic}`
+// is the standard way to match emoji in a JS regex (widely supported);
+// `\p{Emoji_Modifier}` covers skin-tone modifiers, `\u200D` (zero-width
+// joiner) covers compound emoji like family/profession sequences, and
+// `\uFE0F` (variation selector-16) is the explicit emoji-presentation
+// marker some single-codepoint emoji carry -- without all three a real
+// multi-codepoint emoji cluster gets rejected partway through. A custom
+// emoji's `:shortcode:` has no glyph to test against, so it's swapped for
+// a placeholder pictograph first -- same substitution shape as
+// convertCustomEmojiShortcodes above, just standing in for "yes, this is
+// one emoji" rather than an actual image.
+const EMOJI_ONLY_TEST = /^[\p{Extended_Pictographic}\p{Emoji_Modifier}\u200D\uFE0F]+$/u
+// Discord's own cutoff for this treatment -- past a handful, "unusually
+// large emoji" reads as spam rather than expressive, so it reverts to
+// normal size instead of scaling a wall of them up.
+const MAX_EMOJI_ONLY_COUNT = 20
+
+export function isEmojiOnlyMessage(content: string, customShortcodes: Set<string>): boolean {
+  const withBuiltinGlyphs = content.replace(SHORTCODE_PATTERN, (match, name) => EMOJI_SHORTCODES[name] ?? match)
+  const withPlaceholders = withBuiltinGlyphs.replace(CUSTOM_EMOJI_PATTERN, (match, name) =>
+    customShortcodes.has(name) ? '🔹' : match,
+  )
+  const stripped = withPlaceholders.replace(/\s+/g, '')
+  if (!stripped || !EMOJI_ONLY_TEST.test(stripped)) return false
+  return [...new Intl.Segmenter().segment(stripped)].length <= MAX_EMOJI_ONLY_COUNT
+}
+
+// #71: gives every individual unicode emoji its own element (see
+// MarkdownLink's `glyph:` branch) purely so the emoji-size preference can
+// scale it independently of the surrounding text -- a raw emoji is just
+// characters in a string otherwise, with nothing CSS can address on its
+// own. Runs after convertShortcodes so a built-in `:name:` that just
+// became a glyph is wrapped too ("all emoji", not just ones typed as
+// literal unicode); same fence/code-span skip convention as every other
+// converter here.
+const EMOJI_GLYPH_PATTERN = /\p{Extended_Pictographic}(?:\p{Emoji_Modifier}|\u200D\p{Extended_Pictographic}|\uFE0F)*/gu
+
+function wrapEmojiGlyphs(text: string): string {
+  const lines = text.split('\n')
+  let inFence = false
+  return lines
+    .map((line) => {
+      if (/^\s*```/.test(line)) {
+        inFence = !inFence
+        return line
+      }
+      if (inFence) return line
+      return line
+        .split(/(`+[^`]*`+)/g)
+        .map((part, i) => (i % 2 === 0 ? part.replace(EMOJI_GLYPH_PATTERN, (match) => `[${match}](glyph:)`) : part))
+        .join('')
+    })
+    .join('\n')
+}
+
+// Exported so MessageList's reaction pills can apply the same viewer
+// preference to their own EmojiGlyph -- reactions render outside the
+// markdown pipeline entirely (see EmojiGlyph's own comment above), so they
+// need this looked up independently rather than inheriting --emoji-scale
+// from this component's wrapper div.
+export const EMOJI_SCALE_MULTIPLIER: Record<string, number> = {
+  small: 0.8,
+  normal: 1,
+  large: 1.5,
+  xlarge: 2,
+}
+
 export function MessageContent({ content, memberUsernames, myRooms }: MessageContentProps) {
+  const { user } = useAuth()
   const { byShortcode } = useCustomEmoji()
+  const customShortcodes = new Set(byShortcode.keys())
   const withMentions = memberUsernames ? highlightMentions(content, memberUsernames) : content
   const withRoomRefs = myRooms ? highlightRoomReferences(withMentions, myRooms) : withMentions
-  const withCustomEmoji = convertCustomEmojiShortcodes(
-    convertShortcodes(withRoomRefs),
-    new Set(byShortcode.keys()),
+  const withCustomEmoji = convertCustomEmojiShortcodes(convertShortcodes(withRoomRefs), customShortcodes)
+  const withEmojiGlyphs = wrapEmojiGlyphs(withCustomEmoji)
+  const { text, headingIds } = preprocessMarkdown(withEmojiGlyphs)
+  const emojiOnly = isEmojiOnlyMessage(content, customShortcodes)
+  // #71: scoped to this element (not a :root-level variable) so it only
+  // ever affects emoji rendered in message text -- not the same
+  // .message-custom-emoji/EmojiGlyph markup reused by the emoji picker's
+  // grid, where a bigger image would just break its fixed-size layout
+  // instead of doing anything useful. Reaction pills DO scale too, but via
+  // their own inline --emoji-scale in MessageList.tsx, not by inheriting
+  // this one -- a pill isn't a descendant of this wrapper div.
+  const emojiScale = EMOJI_SCALE_MULTIPLIER[user?.emoji_scale ?? 'normal']
+  return (
+    <div
+      className={emojiOnly ? 'message-text-emoji-only' : undefined}
+      style={{ '--emoji-scale': emojiScale } as CSSProperties}
+    >
+      <Markdown options={createMarkdownOptions(headingIds)}>{preserveLineBreaks(text)}</Markdown>
+    </div>
   )
-  const { text, headingIds } = preprocessMarkdown(withCustomEmoji)
-  return <Markdown options={createMarkdownOptions(headingIds)}>{preserveLineBreaks(text)}</Markdown>
 }
diff --git a/frontend/src/components/MessageList.css b/frontend/src/components/MessageList.css
index 01cd062..6bbf712 100644
--- a/frontend/src/components/MessageList.css
+++ b/frontend/src/components/MessageList.css
@@ -53,8 +53,13 @@
 
 .message-image {
   display: block;
-  max-width: min(320px, 100%);
-  max-height: 240px;
+  /* #71: rem, not px -- scales with the text-size setting (see
+     lib/theme.ts's applyTextScale), same as every other size in this app.
+     min(...) still caps against the viewport in absolute px, since a
+     percentage-of-viewport constraint isn't something a root font-size
+     change should affect. */
+  max-width: min(20rem, 100%);
+  max-height: 15rem;
   object-fit: contain;
   border-radius: var(--radius);
   border: 1px solid var(--ds-border);
@@ -65,14 +70,14 @@
 .message-video-wrap {
   position: relative;
   display: inline-block;
-  max-width: min(320px, 100%);
+  max-width: min(20rem, 100%);
   margin-bottom: 4px;
 }
 
 .message-video {
   display: block;
   width: 100%;
-  max-height: 240px;
+  max-height: 15rem;
   border-radius: var(--radius);
   border: 1px solid var(--ds-border);
   background: var(--ds-void);
@@ -111,7 +116,7 @@
   margin-bottom: 4px;
   color: var(--ds-text);
   text-decoration: none;
-  max-width: min(320px, 100%);
+  max-width: min(20rem, 100%);
 }
 
 .message-file-attachment:hover {
diff --git a/frontend/src/components/MessageList.tsx b/frontend/src/components/MessageList.tsx
index 3bf058a..5e6825b 100644
--- a/frontend/src/components/MessageList.tsx
+++ b/frontend/src/components/MessageList.tsx
@@ -1,3 +1,4 @@
+import type { CSSProperties } from 'react'
 import { useEffect, useMemo, useRef, useState } from 'react'
 import { getRoomFileUrl, getRoomImageUrl } from '../api/rooms'
 import { useAuth } from '../context/AuthContext'
@@ -8,7 +9,7 @@ import { EMOJI_PICKER_MAX_HEIGHT, EmojiPicker } from './EmojiPicker'
 import { FilePreviewModal, getPreviewKind } from './FilePreviewModal'
 import { ImageLightbox } from './ImageLightbox'
 import { LinkPreviewCard } from './LinkPreviewCard'
-import { EmojiGlyph, MessageContent } from './MessageContent'
+import { EMOJI_SCALE_MULTIPLIER, EmojiGlyph, MessageContent } from './MessageContent'
 import { UserAvatar } from './UserAvatar'
 import { VideoLightbox } from './VideoLightbox'
 import './MessageList.css'
@@ -126,6 +127,10 @@ export function MessageList({
   onDelete,
 }: MessageListProps) {
   const { user } = useAuth()
+  // #71: same viewer preference MessageContent applies to in-text emoji,
+  // looked up separately here since a reaction pill isn't a descendant of
+  // that component's wrapper div (see EmojiGlyph's own comment).
+  const emojiScale = EMOJI_SCALE_MULTIPLIER[user?.emoji_scale ?? 'normal']
   const containerRef = useRef<HTMLDivElement>(null)
   const bottomRef = useRef<HTMLDivElement>(null)
   // Whether the view should be pinned to the latest message -- true right
@@ -302,7 +307,10 @@ export function MessageList({
                             title={r.user_ids.map(displayNameForUserId).join(', ')}
                             onClick={() => onReact(msg.id, r.emoji)}
                           >
-                            <span>
+                            {/* No .inline-emoji here -- EmojiGlyph's own fallback branch
+                                already applies it, and stacking it here too would double
+                                the font-size multiplication for a custom-emoji img. */}
+                            <span style={{ '--emoji-scale': emojiScale } as CSSProperties}>
                               <EmojiGlyph value={r.emoji} />
                             </span>
                             <span>{r.count}</span>
diff --git a/frontend/src/components/Modal.css b/frontend/src/components/Modal.css
index c7d2cf6..5e271b4 100644
--- a/frontend/src/components/Modal.css
+++ b/frontend/src/components/Modal.css
@@ -230,6 +230,45 @@
   color: var(--ds-muted);
 }
 
+.text-scale-options {
+  display: grid;
+  grid-template-columns: repeat(4, 1fr);
+  gap: var(--sp-2);
+  margin-bottom: var(--sp-4);
+}
+
+.text-scale-option {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 4px;
+  background: var(--ds-surface-2);
+  border: 1px solid var(--ds-border);
+  border-radius: var(--radius);
+  padding: 10px 4px;
+  cursor: pointer;
+}
+
+.text-scale-option:hover {
+  border-color: var(--ds-accent);
+}
+
+.text-scale-option-selected {
+  border-color: var(--ds-accent);
+  box-shadow: 0 0 0 1px var(--ds-accent);
+}
+
+.text-scale-option-preview {
+  font-weight: 700;
+  color: var(--ds-text);
+  line-height: 1;
+}
+
+.text-scale-option-label {
+  font-size: 0.7rem;
+  color: var(--ds-muted);
+}
+
 .theme-swatch-preview-new {
   background: transparent;
   border-style: dashed;
diff --git a/frontend/src/components/ProfileModal.tsx b/frontend/src/components/ProfileModal.tsx
index 9c3ebd8..3de4cb3 100644
--- a/frontend/src/components/ProfileModal.tsx
+++ b/frontend/src/components/ProfileModal.tsx
@@ -5,7 +5,9 @@ import {
   me,
   removeAvatar,
   revokeSession,
+  updateEmojiScale,
   updateProfile,
+  updateTextScale,
   updateTheme,
   uploadAvatar,
 } from '../api/auth'
@@ -20,8 +22,8 @@ import {
 import { getUserAvatarUrl } from '../api/users'
 import { useAuth } from '../context/AuthContext'
 import { hashIndex } from '../lib/avatar'
-import { applyTheme, DEFAULT_CUSTOM_COLORS } from '../lib/theme'
-import type { CustomTheme, CustomThemeColors, UserSession } from '../types'
+import { applyTextScale, applyTheme, DEFAULT_CUSTOM_COLORS } from '../lib/theme'
+import type { CustomTheme, CustomThemeColors, EmojiScale, TextScale, UserSession } from '../types'
 import { ThemeBuilderModal } from './ThemeBuilderModal'
 import { UserAvatar } from './UserAvatar'
 import './Modal.css'
@@ -33,6 +35,26 @@ const THEME_OPTIONS: { name: 'dark' | 'light' | 'midnight' | 'sunset'; label: st
   { name: 'sunset', label: 'Sunset' },
 ]
 
+// #71: the "Aa" preview scales with each option's own size, the standard
+// way a text-size picker shows what it does without a separate demo area.
+const TEXT_SCALE_OPTIONS: { name: TextScale; label: string; previewSize: string }[] = [
+  { name: 'small', label: 'Small', previewSize: '0.8rem' },
+  { name: 'normal', label: 'Normal', previewSize: '1rem' },
+  { name: 'large', label: 'Large', previewSize: '1.25rem' },
+  { name: 'xlarge', label: 'Extra large', previewSize: '1.5rem' },
+]
+
+// #71: independent of text size -- only scales emoji rendered in message
+// text (see MessageContent.tsx's --emoji-scale). The preview uses an
+// actual emoji so it demonstrates itself the same way the text-size
+// options do with "Aa".
+const EMOJI_SCALE_OPTIONS: { name: EmojiScale; label: string; previewSize: string }[] = [
+  { name: 'small', label: 'Small', previewSize: '1rem' },
+  { name: 'normal', label: 'Normal', previewSize: '1.25rem' },
+  { name: 'large', label: 'Large', previewSize: '1.6rem' },
+  { name: 'xlarge', label: 'Extra large', previewSize: '2rem' },
+]
+
 const CUSTOM_COLOR_FIELDS: { key: keyof Omit<CustomThemeColors, 'color_scheme'>; label: string }[] = [
   { key: 'void', label: 'Background' },
   { key: 'void_2', label: 'Sidebar background' },
@@ -60,6 +82,8 @@ export function ProfileModal({ onClose }: ProfileModalProps) {
   const [uploadingAvatar, setUploadingAvatar] = useState(false)
   const fileInputRef = useRef<HTMLInputElement>(null)
   const [themeError, setThemeError] = useState<string | null>(null)
+  const [textScaleError, setTextScaleError] = useState<string | null>(null)
+  const [emojiScaleError, setEmojiScaleError] = useState<string | null>(null)
 
   const [customThemes, setCustomThemes] = useState<CustomTheme[]>([])
   const [editingThemeId, setEditingThemeId] = useState<string | null>(null)
@@ -150,6 +174,32 @@ export function ProfileModal({ onClose }: ProfileModalProps) {
     }
   }
 
+  async function handleSelectTextScale(scale: TextScale) {
+    // Same instant-apply-then-persist pattern as handleSelectPreset above.
+    applyTextScale(scale)
+    setTextScaleError(null)
+    try {
+      const updated = await updateTextScale(scale)
+      updateUser(updated)
+    } catch (err) {
+      applyTextScale(user?.text_scale ?? null)
+      setTextScaleError(err instanceof ApiError ? err.message : String(err))
+    }
+  }
+
+  async function handleSelectEmojiScale(scale: EmojiScale) {
+    // No instant-apply DOM mutation here (unlike theme/text scale) -- it's
+    // just a value MessageContent reads from `user` on its next render, so
+    // persisting and updating that is the whole job.
+    setEmojiScaleError(null)
+    try {
+      const updated = await updateEmojiScale(scale)
+      updateUser(updated)
+    } catch (err) {
+      setEmojiScaleError(err instanceof ApiError ? err.message : String(err))
+    }
+  }
+
   async function handleActivateCustomTheme(theme: CustomTheme) {
     applyTheme('custom', theme.colors)
     setThemeError(null)
@@ -360,6 +410,48 @@ export function ProfileModal({ onClose }: ProfileModalProps) {
         </div>
         {themeError && <p className="modal-error">{themeError}</p>}
 
+        <div className="modal-field-label">Text size</div>
+        <div className="text-scale-options">
+          {TEXT_SCALE_OPTIONS.map((option) => (
+            <button
+              key={option.name}
+              type="button"
+              className={`text-scale-option${
+                (user.text_scale ?? 'normal') === option.name ? ' text-scale-option-selected' : ''
+              }`}
+              onClick={() => handleSelectTextScale(option.name)}
+              aria-pressed={(user.text_scale ?? 'normal') === option.name}
+            >
+              <span className="text-scale-option-preview" style={{ fontSize: option.previewSize }}>
+                Aa
+              </span>
+              <span className="text-scale-option-label">{option.label}</span>
+            </button>
+          ))}
+        </div>
+        {textScaleError && <p className="modal-error">{textScaleError}</p>}
+
+        <div className="modal-field-label">Emoji size</div>
+        <div className="text-scale-options">
+          {EMOJI_SCALE_OPTIONS.map((option) => (
+            <button
+              key={option.name}
+              type="button"
+              className={`text-scale-option${
+                (user.emoji_scale ?? 'normal') === option.name ? ' text-scale-option-selected' : ''
+              }`}
+              onClick={() => handleSelectEmojiScale(option.name)}
+              aria-pressed={(user.emoji_scale ?? 'normal') === option.name}
+            >
+              <span className="text-scale-option-preview" style={{ fontSize: option.previewSize }}>
+                🎉
+              </span>
+              <span className="text-scale-option-label">{option.label}</span>
+            </button>
+          ))}
+        </div>
+        {emojiScaleError && <p className="modal-error">{emojiScaleError}</p>}
+
         <div className="modal-field-label">My custom themes</div>
         <div className="theme-swatch-grid">
           {customThemes.map((theme) => {
diff --git a/frontend/src/context/AuthContext.tsx b/frontend/src/context/AuthContext.tsx
index 0c02d4c..52ef026 100644
--- a/frontend/src/context/AuthContext.tsx
+++ b/frontend/src/context/AuthContext.tsx
@@ -3,7 +3,7 @@ import * as authApi from '../api/auth'
 import { ApiError, NetworkError } from '../api/client'
 import { clearLastUser, loadLastUser, saveLastUser } from '../lib/lastUser'
 import { unsubscribeFromPush } from '../lib/push'
-import { applyTheme } from '../lib/theme'
+import { applyTextScale, applyTheme } from '../lib/theme'
 import type { User } from '../types'
 
 interface AuthContextValue {
@@ -26,6 +26,10 @@ export function AuthProvider({ children }: { children: ReactNode }) {
     applyTheme(user?.theme ?? null, user?.active_custom_theme?.colors ?? null)
   }, [user?.theme, user?.active_custom_theme])
 
+  useEffect(() => {
+    applyTextScale(user?.text_scale ?? null)
+  }, [user?.text_scale])
+
   useEffect(() => {
     authApi
       .me()
diff --git a/frontend/src/lib/theme.ts b/frontend/src/lib/theme.ts
index 137c57d..3c19ab2 100644
--- a/frontend/src/lib/theme.ts
+++ b/frontend/src/lib/theme.ts
@@ -1,4 +1,4 @@
-import type { CustomThemeColors, ThemeName } from '../types'
+import type { CustomThemeColors, TextScale, ThemeName } from '../types'
 
 // The inline custom properties a custom theme sets on :root -- must be
 // removed explicitly when switching to a preset, since an inline style
@@ -76,3 +76,21 @@ export function applyTheme(theme: ThemeName | null, customColors: CustomThemeCol
   for (const varName of CUSTOM_THEME_VARS) root.style.removeProperty(varName)
   root.style.removeProperty('color-scheme')
 }
+
+// #71: percentages, not fixed px -- stacks on top of the browser/OS's own
+// zoom or accessibility text-size setting instead of overriding it. Every
+// component in this app already sizes itself in rem (see tokens.css),
+// which is relative to this root value, so setting it here is the one
+// change that scales text *and* the message-image/video max-size caps
+// (also converted to rem -- see MessageList.css) uniformly, with no
+// per-component work.
+const TEXT_SCALE_PERCENT: Record<TextScale, string> = {
+  small: '87.5%',
+  normal: '100%',
+  large: '112.5%',
+  xlarge: '125%',
+}
+
+export function applyTextScale(scale: TextScale | null): void {
+  document.documentElement.style.fontSize = TEXT_SCALE_PERCENT[scale ?? 'normal']
+}
diff --git a/frontend/src/types.ts b/frontend/src/types.ts
index 08392ff..cb82490 100644
--- a/frontend/src/types.ts
+++ b/frontend/src/types.ts
@@ -1,5 +1,12 @@
 export type ThemeName = 'dark' | 'light' | 'midnight' | 'sunset' | 'custom'
 
+// #71: null means "normal" -- see lib/theme.ts's TEXT_SCALE_PERCENT map.
+export type TextScale = 'small' | 'normal' | 'large' | 'xlarge'
+
+// #71: independent of TextScale -- see MessageContent.tsx's
+// EMOJI_SCALE_MULTIPLIER map. Same preset shape for UI consistency.
+export type EmojiScale = 'small' | 'normal' | 'large' | 'xlarge'
+
 // Matches exactly the CSS custom properties frontend/src/styles/themes.css
 // overrides per built-in preset -- kept in sync with
 // backend/app/schemas/custom_theme.py's CustomThemeColors.
@@ -45,6 +52,8 @@ export interface User {
   // Only non-null when theme === 'custom' -- see UserRead's model_validator
   // in backend/app/schemas/user.py.
   active_custom_theme: CustomTheme | null
+  text_scale: TextScale | null
+  emoji_scale: EmojiScale | null
   avatar_filename: string | null
   appear_offline: boolean
   created_at: string