diff --git a/server/routes/calendar.js b/server/routes/calendar.js
index e966ef5..ca70995 100644
--- a/server/routes/calendar.js
+++ b/server/routes/calendar.js
@@ -11,6 +11,7 @@ import * as db from '../db.js';
 import * as googleCalendar from '../services/google-calendar.js';
 import * as appleCalendar from '../services/apple-calendar.js';
 import * as icsSubscription from '../services/ics-subscription.js';
+import * as caldavSync from '../services/caldav-sync.js';
 import { requireAdmin } from '../auth.js';
 import { str, color, datetime, rrule, collectErrors, MAX_TITLE, MAX_TEXT, DATE_RE, DATETIME_RE } from '../middleware/validate.js';
 import { nextOccurrence } from '../services/recurrence.js';
@@ -817,4 +818,114 @@ router.delete('/:id', (req, res) => {
   }
 });
 
+// --------------------------------------------------------
+// CalDAV Multi-Account Sync Routes
+// --------------------------------------------------------
+
+// Account Management
+
+router.post('/caldav/accounts', requireAdmin, async (req, res) => {
+  try {
+    const { name, caldavUrl, username, password } = req.body;
+
+    if (!name || !caldavUrl || !username || !password) {
+      return res.status(400).json({ error: 'Missing required fields.', code: 400 });
+    }
+
+    const result = await caldavSync.addAccount(name, caldavUrl, username, password);
+    res.json({ data: result });
+  } catch (err) {
+    log.error('CalDAV account creation failed:', err);
+    res.status(500).json({ error: err.message || 'Failed to create CalDAV account.', code: 500 });
+  }
+});
+
+router.get('/caldav/accounts', requireAdmin, (req, res) => {
+  try {
+    const accounts = caldavSync.listAccounts();
+    res.json({ data: accounts });
+  } catch (err) {
+    log.error('CalDAV accounts list failed:', err);
+    res.status(500).json({ error: 'Failed to list CalDAV accounts.', code: 500 });
+  }
+});
+
+router.put('/caldav/accounts/:id', requireAdmin, async (req, res) => {
+  try {
+    const accountId = parseInt(req.params.id, 10);
+    const { name, caldavUrl, username, password } = req.body;
+
+    const result = await caldavSync.updateAccount(accountId, { name, caldavUrl, username, password });
+    res.json({ data: result });
+  } catch (err) {
+    log.error('CalDAV account update failed:', err);
+    res.status(500).json({ error: err.message || 'Failed to update CalDAV account.', code: 500 });
+  }
+});
+
+router.delete('/caldav/accounts/:id', requireAdmin, (req, res) => {
+  try {
+    const accountId = parseInt(req.params.id, 10);
+    const result = caldavSync.deleteAccount(accountId);
+    res.json({ data: result });
+  } catch (err) {
+    log.error('CalDAV account deletion failed:', err);
+    res.status(500).json({ error: err.message || 'Failed to delete CalDAV account.', code: 500 });
+  }
+});
+
+// Calendar Selection
+
+router.get('/caldav/accounts/:id/calendars', requireAdmin, async (req, res) => {
+  try {
+    const accountId = parseInt(req.params.id, 10);
+    const refresh = req.query.refresh === 'true';
+
+    const calendars = await caldavSync.getCalendars(accountId, { refresh });
+    res.json({ data: calendars });
+  } catch (err) {
+    log.error('CalDAV calendars fetch failed:', err);
+    res.status(500).json({ error: err.message || 'Failed to fetch calendars.', code: 500 });
+  }
+});
+
+router.patch('/caldav/accounts/:id/calendars', requireAdmin, (req, res) => {
+  try {
+    const accountId = parseInt(req.params.id, 10);
+    const { calendarUrl, enabled } = req.body;
+
+    if (!calendarUrl || enabled === undefined) {
+      return res.status(400).json({ error: 'Missing calendarUrl or enabled field.', code: 400 });
+    }
+
+    const result = caldavSync.updateCalendarSelection(accountId, calendarUrl, enabled);
+    res.json({ data: result });
+  } catch (err) {
+    log.error('CalDAV calendar selection update failed:', err);
+    res.status(500).json({ error: err.message || 'Failed to update calendar selection.', code: 500 });
+  }
+});
+
+// Sync & Status
+
+router.post('/caldav/sync', requireAdmin, async (req, res) => {
+  try {
+    const result = await caldavSync.sync();
+    res.json({ data: result });
+  } catch (err) {
+    log.error('CalDAV sync failed:', err);
+    res.status(500).json({ error: 'CalDAV sync failed.', code: 500 });
+  }
+});
+
+router.get('/caldav/status', (req, res) => {
+  try {
+    const status = caldavSync.getStatus();
+    res.json({ data: status });
+  } catch (err) {
+    log.error('CalDAV status failed:', err);
+    res.status(500).json({ error: 'Failed to get CalDAV status.', code: 500 });
+  }
+});
+
 export default router;
diff --git a/server/services/caldav-sync.js b/server/services/caldav-sync.js
index 140d16e..86fb2bd 100644
--- a/server/services/caldav-sync.js
+++ b/server/services/caldav-sync.js
@@ -227,6 +227,302 @@ function deleteAccount(accountId) {
   return { success: true };
 }
 
+// --------------------------------------------------------
+// Calendar Selection
+// --------------------------------------------------------
+
+async function getCalendars(accountId, { refresh = false } = {}) {
+  const account = getAccountById(accountId);
+  if (!account) {
+    throw new Error(`Account ${accountId} not found.`);
+  }
+
+  if (!refresh) {
+    // Return from DB
+    const calendars = db.get().prepare(`
+      SELECT calendar_url, calendar_name, calendar_color, enabled
+      FROM caldav_calendar_selection
+      WHERE account_id = ?
+      ORDER BY calendar_name
+    `).all(accountId);
+
+    return calendars.map(cal => ({
+      calendarUrl: cal.calendar_url,
+      calendarName: cal.calendar_name,
+      calendarColor: cal.calendar_color,
+      enabled: cal.enabled === 1,
+    }));
+  }
+
+  // Refresh from server
+  const { calendars } = await testConnection(account.caldav_url, account.username, account.password);
+
+  // Update DB
+  db.get().prepare('DELETE FROM caldav_calendar_selection WHERE account_id = ?').run(accountId);
+
+  const result = [];
+  for (const cal of calendars) {
+    const calColor = normalizeCalColor(cal.calendarColor) || '#4A90E2';
+    const calName = cal.displayName || 'Unnamed Calendar';
+
+    db.get().prepare(`
+      INSERT INTO caldav_calendar_selection (account_id, calendar_url, calendar_name, calendar_color, enabled)
+      VALUES (?, ?, ?, ?, 1)
+    `).run(accountId, cal.url, calName, calColor);
+
+    result.push({
+      calendarUrl: cal.url,
+      calendarName: calName,
+      calendarColor: calColor,
+      enabled: true,
+    });
+  }
+
+  log.info(`Refreshed calendars for account ${accountId}.`);
+
+  return result;
+}
+
+function updateCalendarSelection(accountId, calendarUrl, enabled) {
+  const account = getAccountById(accountId);
+  if (!account) {
+    throw new Error(`Account ${accountId} not found.`);
+  }
+
+  const enabledValue = enabled ? 1 : 0;
+
+  const result = db.get().prepare(`
+    UPDATE caldav_calendar_selection
+    SET enabled = ?
+    WHERE account_id = ? AND calendar_url = ?
+  `).run(enabledValue, accountId, calendarUrl);
+
+  if (result.changes === 0) {
+    throw new Error(`Calendar not found for account ${accountId}.`);
+  }
+
+  log.info(`Calendar selection updated: account ${accountId}, calendar ${calendarUrl}, enabled=${enabled}`);
+
+  return { success: true };
+}
+
+// --------------------------------------------------------
+// Sync
+// --------------------------------------------------------
+
+async function sync() {
+  const accounts = getAllAccounts();
+
+  if (accounts.length === 0) {
+    log.info('No CalDAV accounts configured.');
+    return { success: true, syncedAccounts: 0, syncedEvents: 0 };
+  }
+
+  let totalSyncedEvents = 0;
+  let successfulAccounts = 0;
+
+  for (const account of accounts) {
+    try {
+      log.info(`Syncing CalDAV account ${account.id} ("${account.name}")...`);
+
+      // Create tsdav client
+      const { createDAVClient } = await import('tsdav');
+      const client = await createDAVClient({
+        serverUrl:          account.caldav_url,
+        credentials:        { username: account.username, password: account.password },
+        authMethod:         'Basic',
+        defaultAccountType: 'caldav',
+      });
+
+      // Get enabled calendars for this account
+      const enabledCalendars = db.get().prepare(`
+        SELECT calendar_url, calendar_name, calendar_color
+        FROM caldav_calendar_selection
+        WHERE account_id = ? AND enabled = 1
+      `).all(account.id);
+
+      if (enabledCalendars.length === 0) {
+        log.info(`Account ${account.id}: no enabled calendars, skipping.`);
+        continue;
+      }
+
+      // Fetch all calendars from server
+      const serverCalendars = await client.fetchCalendars();
+
+      // Inbound sync: CalDAV → Oikos
+      let accountEventCount = 0;
+
+      for (const selCal of enabledCalendars) {
+        // Find matching calendar from server
+        const serverCal = serverCalendars.find(sc => sc.url === selCal.calendar_url);
+
+        if (!serverCal) {
+          log.warn(`Calendar ${selCal.calendar_url} not found on server, disabling.`);
+          db.get().prepare(`
+            UPDATE caldav_calendar_selection SET enabled = 0
+            WHERE account_id = ? AND calendar_url = ?
+          `).run(account.id, selCal.calendar_url);
+          continue;
+        }
+
+        // Fetch calendar objects
+        let calObjects;
+        try {
+          calObjects = await client.fetchCalendarObjects({ calendar: serverCal });
+        } catch (err) {
+          log.error(`Failed to fetch calendar objects from ${selCal.calendar_name}:`, err.message);
+          continue;
+        }
+
+        // Upsert external calendar metadata
+        const calRefId = upsertExternalCalendar('caldav', selCal.calendar_url, selCal.calendar_name, selCal.calendar_color);
+
+        // Parse and upsert events
+        for (const obj of calObjects) {
+          const parsed = parseICS(obj.data || '');
+
+          for (const ev of parsed) {
+            try {
+              const existing = db.get().prepare(
+                `SELECT id FROM calendar_events WHERE external_calendar_id = ? AND external_source = 'caldav'`
+              ).get(ev.uid);
+
+              if (existing) {
+                // Update
+                db.get().prepare(`
+                  UPDATE calendar_events
+                  SET title = ?, description = ?, start_datetime = ?, end_datetime = ?,
+                      all_day = ?, location = ?, recurrence_rule = ?, color = ?, calendar_ref_id = ?
+                  WHERE id = ?
+                `).run(
+                  ev.summary, ev.description, ev.dtstart, ev.dtend,
+                  ev.allDay ? 1 : 0, ev.location, ev.rrule, selCal.calendar_color, calRefId, existing.id
+                );
+              } else {
+                // Insert
+                const owner = db.get().prepare('SELECT id FROM users ORDER BY id ASC LIMIT 1').get();
+                const createdBy = owner ? owner.id : 1;
+
+                db.get().prepare(`
+                  INSERT INTO calendar_events
+                    (title, description, start_datetime, end_datetime, all_day,
+                     location, color, external_calendar_id, external_source, recurrence_rule, calendar_ref_id, created_by)
+                  VALUES (?, ?, ?, ?, ?, ?, ?, ?, 'caldav', ?, ?, ?)
+                `).run(
+                  ev.summary, ev.description, ev.dtstart, ev.dtend,
+                  ev.allDay ? 1 : 0, ev.location, selCal.calendar_color, ev.uid, ev.rrule, calRefId, createdBy
+                );
+              }
+
+              accountEventCount++;
+            } catch (err) {
+              log.error(`Failed to upsert event UID ${ev.uid}:`, err.message);
+            }
+          }
+        }
+      }
+
+      // Outbound sync: Oikos → CalDAV (events with target_caldav_account_id)
+      const localEvents = db.get().prepare(`
+        SELECT * FROM calendar_events
+        WHERE external_source = 'local' AND target_caldav_account_id = ?
+      `).all(account.id);
+
+      for (const event of localEvents) {
+        try {
+          // Find target calendar
+          const targetCal = serverCalendars.find(sc => sc.url === event.target_caldav_calendar_url);
+
+          if (!targetCal) {
+            log.warn(`Target calendar ${event.target_caldav_calendar_url} not found, skipping event ${event.id}.`);
+            continue;
+          }
+
+          // Build ICS (need to import buildICS from apple-calendar or define it)
+          // For now, create simple ICS
+          const uid = `oikos-${event.id}@oikos.local`;
+          const icsData = `BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Oikos//CalDAV Sync//EN
+BEGIN:VEVENT
+UID:${uid}
+DTSTART:${event.start_datetime.replace(/[-:]/g, '')}
+DTEND:${event.end_datetime.replace(/[-:]/g, '')}
+SUMMARY:${event.title || ''}
+DESCRIPTION:${event.description || ''}
+END:VEVENT
+END:VCALENDAR`;
+
+          // Upload to CalDAV
+          await client.createCalendarObject({
+            calendar: targetCal,
+            filename: `${uid}.ics`,
+            iCalString: icsData,
+          });
+
+          // Update event to mark as synced
+          db.get().prepare(`
+            UPDATE calendar_events
+            SET external_source = 'caldav', external_calendar_id = ?
+            WHERE id = ?
+          `).run(uid, event.id);
+
+          accountEventCount++;
+        } catch (err) {
+          log.error(`Failed to upload event ${event.id} to CalDAV:`, err.message);
+        }
+      }
+
+      // Update last_sync for account
+      db.get().prepare(`
+        UPDATE caldav_accounts SET last_sync = ? WHERE id = ?
+      `).run(new Date().toISOString(), account.id);
+
+      totalSyncedEvents += accountEventCount;
+      successfulAccounts++;
+
+      log.info(`Account ${account.id} sync complete: ${accountEventCount} events.`);
+
+    } catch (err) {
+      log.error(`Sync failed for account ${account.id}:`, err.message);
+      // Continue with next account (don't abort entire sync)
+    }
+  }
+
+  log.info(`CalDAV sync complete: ${successfulAccounts}/${accounts.length} accounts, ${totalSyncedEvents} events.`);
+
+  return { success: true, syncedAccounts: successfulAccounts, syncedEvents: totalSyncedEvents };
+}
+
+function getStatus() {
+  const accounts = getAllAccounts();
+
+  const accountStatus = accounts.map(acc => {
+    const calendarCount = db.get().prepare(
+      'SELECT COUNT(*) as count FROM caldav_calendar_selection WHERE account_id = ? AND enabled = 1'
+    ).get(acc.id).count;
+
+    return {
+      id: acc.id,
+      name: acc.name,
+      caldavUrl: acc.caldav_url,
+      username: acc.username,
+      lastSync: acc.last_sync,
+      enabledCalendars: calendarCount,
+    };
+  });
+
+  const totalCalendars = db.get().prepare(
+    'SELECT COUNT(*) as count FROM caldav_calendar_selection WHERE enabled = 1'
+  ).get().count;
+
+  return {
+    accounts: accountStatus,
+    totalAccounts: accounts.length,
+    totalEnabledCalendars: totalCalendars,
+  };
+}
+
 // --------------------------------------------------------
 // Exports
 // --------------------------------------------------------
@@ -235,5 +531,9 @@ export {
   addAccount,
   listAccounts,
   updateAccount,
-  deleteAccount
+  deleteAccount,
+  getCalendars,
+  updateCalendarSelection,
+  sync,
+  getStatus
 };