21. Aerodynamics of Gender (Season 2, Episode 7)

Matt Walsh as Joshua, the white supremacist gardener, is one of the shows best guest appearances, but the joy of a petulant Pierce trying to join in Jeff and Troys solitude, and Abed malfunctioning as a bitching robot are a beautiful combination. Plus, the final realisation Jeff has is surprisingly deep, and brings it up on the list.
20. Asian Population Studies (Season 2, Episode 12)

For me, the best episodes of Community arent when the gang are having a wacky, themed, pastiche adventure- though they are so much fun to watch- but actually when they are stuck in a room, arguing. The cast and the writing become the stars here, and most of the episode takes place in the study room. Its also great because of the emotional resonance. Andrés talk with Jeff and his seeking of help from Rich just make it.