The Castle Guide is a supplemental rulebook published in 1990 for the 2nd edition of the Advanced Dungeons & Dragons fantasy role-playing game.

The Castle Guide is a rules supplement intended for the 2nd edition Dungeon Master's Guide which covers life in feudal lands, and how to build, run, siege, and defend castles.

[1] Reviewer Keith H. Eisenbeis stated that it "contains all types of useful and needed information about almost every aspect of castle existence from construction to destruction".

[1] DMGR2 The Castle Guide was written by Grant Boucher, Troy Christensen, Arthur Collins, and Nigel Findley, with Timothy B.

[2] He noted its comprehensiveness and quality, stating that "it successfully balances the reality of a historical medieval castle with all the fantasy elements of an AD&D campaign world.