This article considers three theories of autism: The Theory of Mind Deficit, Executive Dysfunction and the Weak Central Coherence accounts. It outlines each along with studies relevant to their emergence, their expansion, their limitations and their possible integration. Furthermore, consideration is given to any implication from the theories in relation to the distinction or otherwise between the various autistic subgroups. Finally, future directions in autism research are identified, especially in terms of methodological advances and whether the three theories can be unified. (C) 2007 Elsevier Inc. All rights reserved.