Cognitive therapy has been shown effective in the treatment of several psychological and health-related disorders. It is also increasingly used in the management of insomnia. This article outlines some principles and applications of this therapeutic approach as adapted to the treatment of insomnia. Based on Beck's model, this psychotherapeutic approach seeks to modify sleep-related dysfunctional beliefs and thoughts and maladaptive cognitive processes involved in the exacerbation and perpetuation of insomnia. This is accomplished through the use of several cognitive restructuring procedures. After outlining a conceptual model of insomnia, which emphasizes the mediating role of dysfunctional cognitions in the development and maintenance of chronic insomnia, the rationale and general principles of cognitive therapy for insomnia are presented, followed by a description of the treatment procedures, clinical case illustrations, and practical implementation issues. Future directions include the need to refine cognitive interventions and to examine the unique contribution of this therapeutic component to the overall efficacy of multifaceted cognitive-behavioral therapy.