Dunwich Horror is an expansion to Arkham Horror 2nd Edition that includes a new game board and expansion-specific components to support a number of new game mechanics, as well as new core-set components to add more depth to the core game. Released in 2006, it was the second expansion, following the Curse of the Dark Pharaoh expansion released earlier that year, but it was the first "big box" expansion, as Curse did not include a new board.