Investigations of the neural basis of theory of mind - the ability to think about other people's thoughts - only recently became feasible; now, the number of such investigations and the sophistication of the results are accelerating dramatically. The articles in this special issue use a wide range of techniques (including fMRI, EEG, TMS, and psychophisiology) and subject populations (including children, twins, and patients with developmental or acquired neural damage) to address fundamental questions about the cognitive and neural structure of theory of mind. Topics include: (1) the relationship between theory of mind and other, perhaps "precursor", social cognitive processes, such as empathy and the perception of biological motion; (2) the relationship between theory of mind and domain-general cognitive functions, such as executive function and language; and (3) how theory of mind is deployed in real social contexts, such as social exchange.