The majority of cellular diversity in the hippocampus and neocortex derives from a relatively small population of local inhibitory interneurons. Recent technological advances have facilitated the recording and manipulation of defined inhibitory cell classes in awake rodents, revealing new and surprising roles for these cells in local circuit function and behavior. Here we review recent progress in the analysis of inhibitory interneuron subtypes in neocortex and hippocampus during behavior, and suggest opportunities and considerations for extending this research program.