Achievements (Halo: Reach)
From Halopedia, the Halo wiki
There are a total of forty-nine achievements that were shipped with the game totaling 1,000 gamerscore in Halo: Reach: twenty-three Campaign, seven Firefight, four Multiplayer, six Training, and nine Player Experience achievements.
The Noble Map Pack and Defiant Map Pack DLC packs add another ten achievements to Halo: Reach, with seven and three, respectively. An additional three achievements were released for the Defiant Map Pack alongside the release of the Anniversary Map Pack which also included another seven achievements.