diff --git a/web/src/lib/__tests__/settingsSync.test.ts b/web/src/lib/__tests__/settingsSync.test.ts
index 64721d5..0fb78d5 100644
--- a/web/src/lib/__tests__/settingsSync.test.ts
+++ b/web/src/lib/__tests__/settingsSync.test.ts
@@ -25,7 +25,7 @@ describe("which settings follow the account", () => {
     const synced = syncedPart(DEFAULT_SETTINGS);
     // A pane width picked on a monitor is wrong on a laptop, and the
     // notification toggles track a per-browser permission grant.
-    for (const key of ["listPaneWidth", "listPaneHeight", "sidebarWidth", "density", "fontSize", "sidebarCollapsed", "desktopNotifications", "notificationSound"]) {
+    for (const key of ["listPaneWidth", "listPaneHeight", "contactsListWidth", "sidebarWidth", "density", "fontSize", "sidebarCollapsed", "desktopNotifications", "notificationSound"]) {
       expect(synced, key).not.toHaveProperty(key);
     }
   });
diff --git a/web/src/locales/de.ts b/web/src/locales/de.ts
index 717a38e..2131e50 100644
--- a/web/src/locales/de.ts
+++ b/web/src/locales/de.ts
@@ -1215,6 +1215,7 @@ export const catalog: Catalog = {
     "Full screen": "Vollbild",
     "Resize panes": "Bereichsgröße ändern",
     "Resize message list": "Größe der Nachrichtenliste ändern",
+    "Resize contact list": "Größe der Kontaktliste ändern",
     "Resize sidebar": "Größe der Seitenleiste ändern",
     "Hide from list": "Aus der Liste ausblenden",
     "Show in list": "In der Liste einblenden",
diff --git a/web/src/locales/es.ts b/web/src/locales/es.ts
index 7c810ae..b6d8dfd 100644
--- a/web/src/locales/es.ts
+++ b/web/src/locales/es.ts
@@ -1188,6 +1188,7 @@ export const catalog: Catalog = {
     "Full screen": "Pantalla completa",
     "Resize panes": "Cambiar el tamaño de los paneles",
     "Resize message list": "Cambiar el tamaño de la lista de mensajes",
+    "Resize contact list": "Cambiar el tamaño de la lista de contactos",
     "Resize sidebar": "Cambiar el tamaño de la barra lateral",
     "Hide from list": "Ocultar de la lista",
     "Show in list": "Mostrar en la lista",
diff --git a/web/src/locales/fr.ts b/web/src/locales/fr.ts
index e1649d3..676cf33 100644
--- a/web/src/locales/fr.ts
+++ b/web/src/locales/fr.ts
@@ -1193,6 +1193,7 @@ export const catalog: Catalog = {
     "Full screen": "Plein écran",
     "Resize panes": "Redimensionner les volets",
     "Resize message list": "Redimensionner la liste des messages",
+    "Resize contact list": "Redimensionner la liste des contacts",
     "Resize sidebar": "Redimensionner la barre latérale",
     "Hide from list": "Masquer de la liste",
     "Show in list": "Afficher dans la liste",
diff --git a/web/src/locales/ja.ts b/web/src/locales/ja.ts
index cc0e599..c597628 100644
--- a/web/src/locales/ja.ts
+++ b/web/src/locales/ja.ts
@@ -1196,6 +1196,7 @@ export const catalog: Catalog = {
     "Full screen": "全画面",
     "Resize panes": "ペインの大きさを変更",
     "Resize message list": "メール一覧の大きさを変更",
+    "Resize contact list": "連絡先一覧の大きさを変更",
     "Resize sidebar": "サイドバーの大きさを変更",
     "Hide from list": "一覧で非表示にする",
     "Show in list": "一覧に表示する",
diff --git a/web/src/locales/nl.ts b/web/src/locales/nl.ts
index 3437f22..6b6883b 100644
--- a/web/src/locales/nl.ts
+++ b/web/src/locales/nl.ts
@@ -1184,6 +1184,7 @@ export const catalog: Catalog = {
     "Full screen": "Volledig scherm",
     "Resize panes": "Vensterdelen verslepen",
     "Resize message list": "Grootte van de berichtenlijst wijzigen",
+    "Resize contact list": "Grootte van de contactenlijst wijzigen",
     "Resize sidebar": "Grootte van de zijbalk wijzigen",
     "Hide from list": "Verbergen in de lijst",
     "Show in list": "Tonen in de lijst",
diff --git a/web/src/locales/pt-BR.ts b/web/src/locales/pt-BR.ts
index 934f09e..1767f1f 100644
--- a/web/src/locales/pt-BR.ts
+++ b/web/src/locales/pt-BR.ts
@@ -1191,6 +1191,7 @@ export const catalog: Catalog = {
     "Full screen": "Tela cheia",
     "Resize panes": "Redimensionar os painéis",
     "Resize message list": "Redimensionar a lista de mensagens",
+    "Resize contact list": "Redimensionar a lista de contatos",
     "Resize sidebar": "Redimensionar a barra lateral",
     "Hide from list": "Ocultar da lista",
     "Show in list": "Mostrar na lista",
diff --git a/web/src/locales/ru.ts b/web/src/locales/ru.ts
index a5915da..8bdf1ae 100644
--- a/web/src/locales/ru.ts
+++ b/web/src/locales/ru.ts
@@ -1190,6 +1190,7 @@ export const catalog: Catalog = {
     "Full screen": "Во весь экран",
     "Resize panes": "Изменить размер панелей",
     "Resize message list": "Изменить размер списка писем",
+    "Resize contact list": "Изменить размер списка контактов",
     "Resize sidebar": "Изменить размер боковой панели",
     "Hide from list": "Скрыть из списка",
     "Show in list": "Показать в списке",
diff --git a/web/src/locales/uk.ts b/web/src/locales/uk.ts
index e5669ef..0aa6e7e 100644
--- a/web/src/locales/uk.ts
+++ b/web/src/locales/uk.ts
@@ -1184,6 +1184,7 @@ export const catalog: Catalog = {
     "Full screen": "На весь екран",
     "Resize panes": "Змінити розмір панелей",
     "Resize message list": "Змінити розмір списку листів",
+    "Resize contact list": "Змінити розмір списку контактів",
     "Resize sidebar": "Змінити розмір бічної панелі",
     "Hide from list": "Сховати зі списку",
     "Show in list": "Показати в списку",
diff --git a/web/src/locales/zh-Hans.ts b/web/src/locales/zh-Hans.ts
index ec1d87f..e4035fd 100644
--- a/web/src/locales/zh-Hans.ts
+++ b/web/src/locales/zh-Hans.ts
@@ -1195,6 +1195,7 @@ export const catalog: Catalog = {
     "Full screen": "全屏",
     "Resize panes": "调整窗格大小",
     "Resize message list": "调整邮件列表大小",
+    "Resize contact list": "调整联系人列表大小",
     "Resize sidebar": "调整侧边栏大小",
     "Hide from list": "从列表中隐藏",
     "Show in list": "在列表中显示",
diff --git a/web/src/store/settings.ts b/web/src/store/settings.ts
index 4ee9a27..91d8c09 100644
--- a/web/src/store/settings.ts
+++ b/web/src/store/settings.ts
@@ -256,6 +256,8 @@ export interface Settings {
   listPaneWidth: number;
   /** Height (px) of the message list when the reading pane is below. */
   listPaneHeight: number;
+  /** Width (px) of the contact list, beside the contact on show. */
+  contactsListWidth: number;
   /**
    * Width (px) of the sidebar, dragged by its edge (#345). Null until someone
    * drags it, and null again after a double-click resets it -- which leaves the
@@ -377,6 +379,7 @@ export const DEFAULT_SETTINGS: Settings = {
   sendAndArchive: false,
   listPaneWidth: 520,
   listPaneHeight: 340,
+  contactsListWidth: 320,
   sidebarWidth: null,
   eventCategories: [
     { name: "Important", color: "#dc2626" },
@@ -408,6 +411,7 @@ export const DEVICE_KEYS: ReadonlySet<keyof Settings> = new Set<keyof Settings>(
   "notificationSound",
   "listPaneWidth",
   "listPaneHeight",
+  "contactsListWidth",
   "sidebarWidth",
 ]);
 
diff --git a/web/src/styles/app.css b/web/src/styles/app.css
index f8bbc62..c6f7216 100644
--- a/web/src/styles/app.css
+++ b/web/src/styles/app.css
@@ -1753,8 +1753,7 @@ select optgroup { background-color: var(--bg-elev); color: var(--fg); }
 /* ==========================================================================
    Contacts
    ========================================================================== */
-.contacts-layout { display: grid; grid-template-columns: 220px minmax(280px, 360px) 1fr; height: 100%; min-height: 0; flex: 1; }
-.contacts-books { border-right: 1px solid var(--border); padding: 12px 8px; overflow-y: auto; overflow-x: hidden; }
+.contacts-layout { display: grid; grid-template-columns: var(--list-size, 320px) auto minmax(0, 1fr); height: 100%; min-height: 0; flex: 1; }
 .contacts-list { border-right: 1px solid var(--border); display: flex; flex-direction: column; min-height: 0; }
 .contacts-list .list-search { padding: 10px 12px; border-bottom: 1px solid var(--border); }
 .contacts-scroll { flex: 1; overflow-y: auto; }
@@ -2015,7 +2014,6 @@ select optgroup { background-color: var(--bg-elev); color: var(--fg); }
 @media (max-width: 1100px) {
   :root { --list-w: 44%; }
   .msg-row .msg-from { width: 140px; }
-  .contacts-layout { grid-template-columns: 200px 300px 1fr; }
 }
 @media (max-width: 900px) {
   .mail-layout:not(.pane-off):not(.pane-bottom) { grid-template-columns: 1fr !important; }
@@ -2036,7 +2034,7 @@ select optgroup { background-color: var(--bg-elev); color: var(--fg); }
   .admin-table .hide-mobile { display: none; }
   .admin-sheet { width: 100%; border-left: 0; box-shadow: none; }
   .contacts-layout { grid-template-columns: 1fr; }
-  .contacts-books { display: none; }
+  .contacts-layout .splitter { display: none; }
   .contacts-layout.detail .contacts-list { display: none; }
   .contacts-layout:not(.detail) .contact-detail { display: none; }
   .cal-layout { grid-template-columns: 1fr; }
diff --git a/web/src/views/contacts/ContactsView.tsx b/web/src/views/contacts/ContactsView.tsx
index dc64d12..1b40658 100644
--- a/web/src/views/contacts/ContactsView.tsx
+++ b/web/src/views/contacts/ContactsView.tsx
@@ -10,6 +10,8 @@ import { formatDate, formatDateLong } from "@/lib/datetime";
 import { Avatar, Empty, Spinner, useIsNarrow } from "@/ui/misc";
 import { confirmDialog } from "@/ui/dialog";
 import { toast } from "@/ui/toast";
+import { Splitter } from "@/ui/Splitter";
+import { useSettings } from "@/store/settings";
 import { ContactEditor } from "./ContactEditor";
 import { avatarColor } from "@/lib/address";
 import { plural, t as translate } from "@/lib/i18n";
@@ -18,6 +20,14 @@ export function ContactsView({ id }: { id?: string }) {
   const [, navigate] = useLocation();
   const contacts = useContacts();
   const narrow = useIsNarrow();
+  const listWidth = useSettings((s) => s.settings.contactsListWidth);
+  const updateSettings = useSettings((s) => s.update);
+  const layoutRef = useRef<HTMLDivElement>(null);
+  /* The width mid-drag, and a ref mirroring it for the end of a key press,
+     which follows the resize in the same tick -- the same pair as the mail
+     list's splitter, for the same reason. */
+  const [liveWidth, setLiveWidth] = useState<number | null>(null);
+  const liveWidthRef = useRef<number | null>(null);
   const [q, setQ] = useState("");
   /* The book being shown lives in the store, because the list that chooses it
      is the app's own sidebar rather than anything this view owns. */
@@ -240,8 +250,23 @@ export function ContactsView({ id }: { id?: string }) {
     }
   };
 
+  const shownListWidth = liveWidth ?? listWidth;
+  const onSplit = (delta: number) => {
+    const total = layoutRef.current?.clientWidth ?? 1200;
+    const max = Math.max(240, total - 360);
+    const next = Math.min(max, Math.max(240, (liveWidthRef.current ?? shownListWidth) + delta));
+    liveWidthRef.current = next;
+    setLiveWidth(next);
+  };
+  const onSplitEnd = () => {
+    const width = liveWidthRef.current;
+    liveWidthRef.current = null;
+    setLiveWidth(null);
+    if (width != null) updateSettings({ contactsListWidth: width });
+  };
+
   return (
-    <div className={`contacts-layout ${selected || editing ? "detail" : ""}`}>
+    <div ref={layoutRef} className={`contacts-layout ${selected || editing ? "detail" : ""}`} style={{ "--list-size": `${shownListWidth}px` } as React.CSSProperties}>
 
       <section className="contacts-list">
         {pickedIds.length ? (
@@ -303,6 +328,7 @@ export function ContactsView({ id }: { id?: string }) {
           ))}
         </div>
       </section>
+      {!narrow && <Splitter direction="vertical" onResize={onSplit} onEnd={onSplitEnd} onReset={() => updateSettings({ contactsListWidth: 320 })} ariaLabel={translate("Resize contact list")} />}
 
       <section className="contact-detail">
         {selected ? (