The Division was formed at Edinburgh on 1 September 1938 within Scottish Command, transferring to Anti-Aircraft Command when that formation was created on 1 April 1939. It was responsible for the Anti-Aircraft defences of Scotland, Northern Ireland and the Orkney and Shetland Defences (OSDEF).
In August 1942 the Divisional HQ moved south to join 1 Anti-Aircraft Corps and was given control of the 6, 27 (Home Counties) and 47 Anti-Aircraft Brigades. At the end of September 1942, all the Anti-Aircraft Divisional HQs were disbanded and 3 Division merged with 12 Anti-Aircraft Division in the newly formed 6 Anti-Aircraft Group
Order of Battle 1938-39
| 3 Anti-Aircraft Brigade – formed 7 December 1938 at Belfast |
| 3 (Ulster) Searchlight Regiment – formed 1939 |
| 8 (Belfast) Anti-Aircraft Regiment – formed 1939 |
| 9 (Londonderry) Anti-Aircraft Regiment – formed 1939 |
| 102 Anti-Aircraft Regiment – formed at Antrim 10 Sep 39 |
| 36 (Scottish) Anti-Aircraft Brigade – formed 1 May 1938 at Edinburgh, responsible for the city of Edinburgh and the Firth of Forth |
| 71 (Forth) Anti-Aircraft Regiment – formed 1938 at Dunfermline |
| 94 Anti-Aircraft Regiment – formed Apr 39 at Turnhouse |
| 101 Anti-Aircraft Regiment – formed Aug 39 at Inverness |
| 42 Anti-Aircraft Brigade – formed 1 October 1938 at Glasgow, responsible for the city of Glasgow and the Firth of Clyde |
| 74 (City of Glasgow) Anti-Aircraft Regiment |
| 83 (Blythswood) Anti-Aircraft Regiment – converted 1938 from the 7th (Blythswood) Battalion, Highland Light Infantry |
| 100 Anti-Aircraft Regiment – formed at Motherwell |
| 43 Anti-Aircraft Brigade – formed 1 October 1938 at West Hartlepool. Transferred to 7 Anti-Aircraft Division July 1939 |
| 85 (Tees) Anti-Aircraft Regiment |
| 47 (Durham Light Infantry) Anti-Aircraft Battalion RE |
| 1/5 Battalion Durham Light Infantry (54 Searchlight Regiment) |
| 2/5 Battalion Durham Light Infantry (55 Searchlight Regiment) |
| 51 Light Anti-Aircraft Brigade – formed 25 August 1939 at Edinburgh, originally to command the Light Anti-Aircraft units of the 3 Anti-Aircraft Division, but later assumed responsibility for north east Scotland |
| 14 (West Lothian Royal Scots) Light Anti-Aircraft Regiment – converted Aug 38 from part of the 4th/5th Battalion Royal Scots at Linlithgow |
| 18 Light Anti-Aircraft Regiment – formed Dec 38 at Glasgow |
| 19 Light Anti-Aircraft Regiment – formed Jan 39 at Edinburgh |
| 31 Light Anti-Aircraft Regiment – formed Aug 39 at Perth |
| 32 Light Anti-Aircraft Regiment – formed Aug 39 at Falkirk |
| 52 Light Anti-Aircraft Brigade – formed August 1939 at Stirling with responsibility for searchlight provision across the 3 Anti-Aircraft Division’s sectors |
| 51 (Highland) Anti-Aircraft Battalion, Royal Engineers – formed in 1938 at Aberdeen |
| 4th/5th Battalion, Royal Scots (52 Searchlight Regiment) – converted 1938 from part of the 4th/5th Battalion in central Edinburgh |
| 5th Battalion, Cameronians (Scottish Rifles) (56 Searchlight Regiment) – converted 1938 from 5/8th Battalion Cameronians (Scottish Rifles) at Glasgow |
| 8th Battalion, Cameronians (Scottish Rifles) (57 Searchlight Regiment) – formed 1 November 1938 by duplication of the above, based in south Glasgow |
Order of Battle 1940-41
| 36 Anti-Aircraft Brigade – Edinburgh & Forth |
| 71 Heavy Anti-Aircraft Regiment – left Oct 41 |
| 114 Heavy Anti-Aircraft Regiment – formed Nov 40 |
| 31 Light Anti-Aircraft Regiment |
| 32 Light Anti-Aircraft Regiment |
| 51 Anti-Aircraft Brigade – North East Scotland |
| 108 Heavy Anti-Aircraft Regiment – formed Aug 40 |
| 40 Light Anti-Aircraft Regiment – formed Sep 39 |
| 67 Light Anti-Aircraft Regiment– formed Dec 40 |
| 52 Anti-Aircraft Brigade – Searchlights |
| 51 Searchlight Regiment |
| 52 Searchlight Regiment |
| 56 Searchlight Regiment |
Order of Battle 1942
| 36 Anti-Aircraft Brigade |
| 114 Heavy Anti-Aircraft Regiment – to 51 Anti-Aircraft Brigade May 42 |
| 129 (Mixed) Heavy Anti-Aircraft Regiment – formed Aug 41 |
| 19 Light Anti-Aircraft Regiment – joined 1941; left Feb 42 |
| 20 Light Anti-Aircraft Regiment – joined 1942; left Jun 42 |
| 72 Light Anti-Aircraft Regiment – joined Aug 41; left Apr 42 |
| 95 Light Anti-Aircraft Regiment – joined from the 51 Anti-Aircraft Brigade Jun 42 |
| 135 Light Anti-Aircraft Regiment – formed Feb 42; to 52 Anti-Aircraft Brigade Jun 42 |
| 46 (Lincolnshire Regiment) Searchlight Regiment – joined Spring 42 |
| 51 Anti-Aircraft Brigade |
| 65 (Manchester Regiment) Heavy Anti-Aircraft Regiment – joined and left Dec 41 |
| 100 Heavy Anti-Aircraft Regiment – joined Jun 42 |
| 101 Heavy Anti-Aircraft Regiment – joined Jun 41; left Jun 42 |
| 108 Heavy Anti-Aircraft Regiment – left Jun 41 |
| 114 Heavy Anti-Aircraft Regiment – from 36 Anti-Aircraft Brigade May 42 |
| 40 Light Anti-Aircraft Regiment – transferred to 51st (Highland) Division May 42 |
| 67 Light Anti-Aircraft Regiment – to 52 Anti-Aircraft Brigade |
| 95 Light Anti-Aircraft Regiment – formed Nov 41; to 36 Anti-Aircraft Brigade Jun 42 |
| 131 Light Anti-Aircraft Regiment – joined Jun 42 |
| 52nd Anti-Aircraft Brigade |
| 147 Heavy Anti-Aircraft Regiment – formed Feb 42 |
| 67 Light Anti-Aircraft Regiment – from 51 Anti-Aircraft Brigade Spring 42; left Jun 42 |
| 135 Light Anti-Aircraft Regiment – from 36 Anti-Aircraft Brigade Spring 42 |
| 51 Searchlight Regiment – left and became the 124 (Highland) Light Anti-Aircraft Regiment Feb 42 |
| 52 Searchlight Regiment – became the 130 (Queen’s Edinburgh, Royal Scots) Light Anti-Aircraft Regiment Mar 42 and remained with brigade |
| 56 Searchlight Regiment – left and became the 125 (Cameronians) Light Anti-Aircraft Regiment in Feb 42 |