Helen Steward puts forward a radical critique of the foundations of contemporary philosophy of mind, arguing that it relies too heavily on insecure assumptions about the nature of some of the sorts of mental entities it postulates–the nature of events, processes, and states. She offers a fresh investigation of these three categories, clarifying the distinction between them, and argues specifically that the assumption that states can be treated as particular, event-like entities has been a huge and serious mistake. Steward argues that the category of token state should be rejected, and develops an alternative way of understanding those varieties of causal explanation which have sometimes been thought to require an ontology of token states for their elucidation. She contends that many current theories of mind are rendered unintelligible once it is seen how these explanations really work. A number of prominent features of contemporary philosophy of mind–token identity theories, the functionalists conception of causal role, a common form of argument for eliminative materialism, and the structure of the debate about the efficacy of mental content–are impugned by her arguments. Steward concludes that the modern mind-body problem needs to be substantially rethought.