diff --git a/src/routes/admin/+page.svelte b/src/routes/admin/+page.svelte
index 0ea8801..a93d8af 100644
--- a/src/routes/admin/+page.svelte
+++ b/src/routes/admin/+page.svelte
@@ -27,6 +27,116 @@
   let groupFormSnapshot = $state<Partial<Group>>({});
   let groupFieldError = $state<string | null>(null); // which field has error
 
+  // ── Drag-to-reorder state ─────────────────────────────────────────────────────
+  let dragGroupId = $state<string | null>(null);      // group being dragged
+  let dragOverGroupId = $state<string | null>(null);  // group being hovered over
+  let dragUnitId = $state<string | null>(null);       // unit being dragged
+  let dragUnitGroupId = $state<string | null>(null);  // group of unit being dragged
+  let dragOverUnitId = $state<string | null>(null);   // unit being hovered over
+
+  // ── Drag handlers: groups ─────────────────────────────────────────────────────
+  function onGroupDragStart(e: DragEvent, groupId: string) {
+    dragGroupId = groupId;
+    e.dataTransfer!.effectAllowed = 'move';
+    e.dataTransfer!.setData('text/plain', groupId);
+  }
+
+  function onGroupDragOver(e: DragEvent, groupId: string) {
+    if (!dragGroupId || dragGroupId === groupId) return;
+    e.preventDefault();
+    e.dataTransfer!.dropEffect = 'move';
+    dragOverGroupId = groupId;
+  }
+
+  function onGroupDragLeave(groupId: string) {
+    if (dragOverGroupId === groupId) dragOverGroupId = null;
+  }
+
+  function onGroupDrop(e: DragEvent, targetGroupId: string) {
+    e.preventDefault();
+    if (!dragGroupId || dragGroupId === targetGroupId) {
+      dragGroupId = null;
+      dragOverGroupId = null;
+      return;
+    }
+    // Reorder in local state immediately
+    const groups = [...unitsData.groups];
+    const fromIdx = groups.findIndex((g) => g.id === dragGroupId);
+    const toIdx = groups.findIndex((g) => g.id === targetGroupId);
+    if (fromIdx === -1 || toIdx === -1) { dragGroupId = null; dragOverGroupId = null; return; }
+    const [moved] = groups.splice(fromIdx, 1);
+    groups.splice(toIdx, 0, moved);
+    unitsData = { ...unitsData, groups };
+    dragGroupId = null;
+    dragOverGroupId = null;
+    // Persist
+    fetch('/admin/api/order', {
+      method: 'PUT',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ groups: groups.map((g) => g.id) })
+    });
+  }
+
+  function onGroupDragEnd() {
+    dragGroupId = null;
+    dragOverGroupId = null;
+  }
+
+  // ── Drag handlers: units ──────────────────────────────────────────────────────
+  function onUnitDragStart(e: DragEvent, unitId: string, groupId: string | null) {
+    dragUnitId = unitId;
+    dragUnitGroupId = groupId;
+    e.dataTransfer!.effectAllowed = 'move';
+    e.dataTransfer!.setData('text/plain', unitId);
+  }
+
+  function onUnitDragOver(e: DragEvent, unitId: string, groupId: string | null) {
+    if (!dragUnitId || dragUnitId === unitId || dragUnitGroupId !== groupId) return;
+    e.preventDefault();
+    e.dataTransfer!.dropEffect = 'move';
+    dragOverUnitId = unitId;
+  }
+
+  function onUnitDragLeave(unitId: string) {
+    if (dragOverUnitId === unitId) dragOverUnitId = null;
+  }
+
+  function onUnitDrop(e: DragEvent, targetUnitId: string, groupId: string | null) {
+    e.preventDefault();
+    if (!dragUnitId || dragUnitId === targetUnitId || dragUnitGroupId !== groupId) {
+      dragUnitId = null;
+      dragUnitGroupId = null;
+      dragOverUnitId = null;
+      return;
+    }
+    // Reorder in local state
+    const units = [...unitsData.units];
+    const fromIdx = units.findIndex((u) => u.id === dragUnitId);
+    const toIdx = units.findIndex((u) => u.id === targetUnitId);
+    if (fromIdx === -1 || toIdx === -1) { dragUnitId = null; dragUnitGroupId = null; dragOverUnitId = null; return; }
+    const [moved] = units.splice(fromIdx, 1);
+    units.splice(toIdx, 0, moved);
+    unitsData = { ...unitsData, units };
+    const gid = dragUnitId;
+    dragUnitId = null;
+    dragUnitGroupId = null;
+    dragOverUnitId = null;
+    // Build ordered IDs for this group
+    const groupKey = groupId ?? 'null';
+    const groupUnitIds = units.filter((u) => (u.group ?? null) === groupId).map((u) => u.id);
+    fetch('/admin/api/order', {
+      method: 'PUT',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ units: { [groupKey]: groupUnitIds } })
+    });
+  }
+
+  function onUnitDragEnd() {
+    dragUnitId = null;
+    dragUnitGroupId = null;
+    dragOverUnitId = null;
+  }
+
   // ── Load data ────────────────────────────────────────────────────────────────
   async function loadData() {
     const [res, gres] = await Promise.all([
@@ -470,8 +580,17 @@
     <!-- Group tree -->
     {#each unitsData.groups as group (group.id)}
       {@const groupUnits = unitsByGroup.get(group.id) ?? []}
-      <div class="tree-group">
-        <div class="tree-group-header">
+      <div
+        class="tree-group"
+        class:drag-over-group={dragOverGroupId === group.id}
+        draggable="true"
+        ondragstart={(e) => onGroupDragStart(e, group.id)}
+        ondragover={(e) => onGroupDragOver(e, group.id)}
+        ondragleave={() => onGroupDragLeave(group.id)}
+        ondrop={(e) => onGroupDrop(e, group.id)}
+        ondragend={onGroupDragEnd}
+      >
+        <div class="tree-group-header" class:dragging={dragGroupId === group.id}>
           <!-- Expand toggle -->
           <button
             class="plain expand-btn"
@@ -510,7 +629,20 @@
               <div
                 class="tree-unit-row"
                 class:selected={selectedItem?.id === unit.id && selectedItem?.type === 'unit'}
+                class:drag-over-unit={dragOverUnitId === unit.id}
+                draggable="false"
+                ondragover={(e) => onUnitDragOver(e, unit.id, unit.group ?? null)}
+                ondragleave={() => onUnitDragLeave(unit.id)}
+                ondrop={(e) => onUnitDrop(e, unit.id, unit.group ?? null)}
               >
+                <!-- Drag handle -->
+                <span
+                  class="drag-handle"
+                  draggable="true"
+                  ondragstart={(e) => onUnitDragStart(e, unit.id, unit.group ?? null)}
+                  ondragend={onUnitDragEnd}
+                  title="Drag to reorder"
+                >⠿</span>
                 <input
                   type="checkbox"
                   checked={checkedUnitIds.has(unit.id)}
@@ -550,7 +682,21 @@
         </div>
         <div class="tree-units">
           {#each orphaned as unit (unit.id)}
-            <div class="tree-unit-row" class:selected={selectedItem?.id === unit.id && selectedItem?.type === 'unit'}>
+            <div
+              class="tree-unit-row"
+              class:selected={selectedItem?.id === unit.id && selectedItem?.type === 'unit'}
+              class:drag-over-unit={dragOverUnitId === unit.id}
+              ondragover={(e) => onUnitDragOver(e, unit.id, null)}
+              ondragleave={() => onUnitDragLeave(unit.id)}
+              ondrop={(e) => onUnitDrop(e, unit.id, null)}
+            >
+              <span
+                class="drag-handle"
+                draggable="true"
+                ondragstart={(e) => onUnitDragStart(e, unit.id, null)}
+                ondragend={onUnitDragEnd}
+                title="Drag to reorder"
+              >⠿</span>
               <input
                 type="checkbox"
                 checked={checkedUnitIds.has(unit.id)}
@@ -988,4 +1134,31 @@
   .modal-card { width: 100%; max-width: 480px; margin: 0 1rem; }
   .reassign-options { margin: 0.5rem 0 0.5rem 1.5rem; display: flex; flex-direction: column; gap: 0.5rem; }
   .radio-stack { display: flex; flex-direction: column; gap: 0.25rem; }
+
+  /* ── Drag-to-reorder ───────────────────────────────────────────────────────── */
+  .tree-group-header {
+    cursor: grab;
+  }
+  .tree-group-header.dragging {
+    cursor: grabbing;
+    opacity: 0.5;
+  }
+  .drag-over-group > .tree-group-header {
+    border-top: 2px solid var(--pico-primary);
+  }
+  .drag-handle {
+    cursor: grab;
+    color: var(--pico-muted-color);
+    font-size: 0.9rem;
+    padding: 0 0.1rem;
+    flex-shrink: 0;
+    user-select: none;
+    line-height: 1;
+  }
+  .drag-handle:active {
+    cursor: grabbing;
+  }
+  .drag-over-unit {
+    border-top: 2px solid var(--pico-primary);
+  }
 </style>
diff --git a/src/routes/admin/api/order/+server.ts b/src/routes/admin/api/order/+server.ts
new file mode 100644
index 0000000..8f7feb9
--- /dev/null
+++ b/src/routes/admin/api/order/+server.ts
@@ -0,0 +1,58 @@
+import { json } from '@sveltejs/kit';
+import { loadData, saveData } from '$lib/server/data';
+import { authRequest } from '$lib/server/auth';
+import type { RequestHandler } from './$types';
+
+export const PUT: RequestHandler = async ({ request }) => {
+  if (!authRequest(request)) return json({ error: 'Unauthorized' }, { status: 401 });
+
+  const body = await request.json().catch(() => null);
+  if (!body) return json({ error: 'Invalid JSON' }, { status: 400 });
+
+  const { groups: groupOrder, units: unitOrder } = body as {
+    groups?: string[];
+    units?: Record<string, string[]>;
+  };
+
+  const data = loadData();
+
+  // Reorder groups if provided
+  if (Array.isArray(groupOrder)) {
+    const groupMap = new Map(data.groups.map((g) => [g.id, g]));
+    // Put known IDs first in the new order, then append any not in the list
+    const reordered = groupOrder
+      .map((id) => groupMap.get(id))
+      .filter((g): g is NonNullable<typeof g> => g !== undefined);
+    const mentioned = new Set(groupOrder);
+    const rest = data.groups.filter((g) => !mentioned.has(g.id));
+    data.groups = [...reordered, ...rest];
+  }
+
+  // Reorder units within groups if provided
+  if (unitOrder && typeof unitOrder === 'object') {
+    for (const [groupId, orderedIds] of Object.entries(unitOrder)) {
+      const key = groupId === 'null' ? null : groupId;
+      if (!Array.isArray(orderedIds)) continue;
+      // Build a map of id → unit for units in this group
+      const groupUnits = data.units.filter((u) => (u.group ?? null) === key);
+      const unitMap = new Map(groupUnits.map((u) => [u.id, u]));
+      // Build new ordered list for this group
+      const reordered = orderedIds
+        .map((id) => unitMap.get(id))
+        .filter((u): u is NonNullable<typeof u> => u !== undefined);
+      const mentioned = new Set(orderedIds);
+      const rest = groupUnits.filter((u) => !mentioned.has(u.id));
+      const newGroupUnits = [...reordered, ...rest];
+      // Replace units in data.units for this group, preserving other groups' positions
+      let gi = 0;
+      for (let i = 0; i < data.units.length; i++) {
+        if ((data.units[i].group ?? null) === key) {
+          data.units[i] = newGroupUnits[gi++];
+        }
+      }
+    }
+  }
+
+  saveData(data);
+  return json({ ok: true });
+};