In this short review, we consider the application of transcranial magnetic stimulation (TMS) to the study of cognitive function. Following an introduction to the technique, we consider its possible mechanisms of action. We then review the studies that have applied TMS to the investigation of cognition. In the majority of these investigations, TMS has been applied to disrupt function and demonstrate that a particular cortical area is essential for performance of the task under study. Finally, we highlight pertinent design and procedural issues and consider other types of questions that can be addressed by future TMS studies of cognitive function.