This article reviews some of the recent conceptual and empirical developments in cognitive therapy. It is argued that one of the strengths of the cognitive therapy tradition has been its focus on the quantification of treatment effects, but that in recent years the development of theory and practice has surpassed the data necessary to provide a foundation for these developments. Potential reasons for rapid growth are cited, and some boundaries to research and practice that may emerge are highlighted. The article concludes with a statement of risks associated with too-rapid expansion of theory and practice, and a call for controlled research to substantiate treatment effects.There is little doubt that one of the revolutionary forces within modem psychotherapy has been the cognitive-behavioural therapies. American data suggest that four of the seven most influential psychotherapy writers of history are from the cognitive-behavioural tradition (, 1982;Warner, 1991) and within Canada a recent survey of clinical psychologists has shown that the single most common self-description of a specific theoretical orientation (after eclectic; 33.2 %) used by clinical psychologists is cognitive-behavioural(27.5 %; Warner, 1991). It might also be noted that in the Warner study the cognitivebehavioural self-descriptor was much more popular that the next most common, which was psychoanalytic (9.5 %). Finally, it appears that the percentage of psychologists ascribing to the cognitive-behavioural perspective is going up (Arnett, Martin, Streiner, & Goodman, 1987;Norcross, Prochaska, & Gallagher, 1989;Smith, 1982;Warner, 1991).Within the cognitive-behavioural tradition, there are a number of specific therapy models (Dobson, 1988). These therapy models share three fundamental propositions: (a) cognitive activity affects behaviour, (b) cognitive activity may be monitored and altered, and (c) desired behaviour change may be affected through cognitive change (Dobson & Block, 1988). Thus, while the specific nature of the cognitive activity assessed and targeted for change varies from therapy model to model, and the nature of behavioural change varies as the focus of therapy varies, these models all target both cognitive and behavioural change.Within the cognitive-behavioural tradition, one of the most established treatment models is that developed by Aaron T. Beck and his associates, referred to as cognitive therapy. This model assumes that human dysfunction is predisposed by dysfunctional beliefs (also referred to as schemata or assumptions), which are activated by events that impinge upon those beliefs, and then is mediated through specific negative appraisals, perceptions, and biased processing of current experience (Beck, 1976;Beck & Emery, 1985;Beck, Rush, Shaw, & Emery, 1979). Cognitive therapy is a complex process that involves the systematic assessment and modification of dysfunctional behaviour, biased perceptions, and underlying beliefs.There are a number of reasons for the rapid growth of cognitive therapy. The model was articu...