Chronic insomnia affects nearly 16% of adults and up to 25% of children. Many clinicians are unfamiliar with the research and practice of psychological treatments of insomnia and thus do not use them with their patients. The primary goals of this article were to (a) review the research support for psychological treatments of adult and child insomnia, and (b) describe those treatments with the highest level of research support in enough detail to allow practitioners to begin to utilize them with their own patients. The adult psychological treatments with the best research support are stimulus control, progressive muscle relaxation, and multimodal cognitive–behavioral therapy, followed by multimodal behavioral therapy, sleep restriction, biofeedback, and paradoxical intention. The child psychological treatments with the highest level of research support are preventive parent education, unmodified extinction, and extinction with parental presence, followed by graduated extinction, bedtime fading/positive routines, and scheduled awakenings. © 2010 Wiley Periodicals, Inc. J Clin Psychol: In Session 66:1–11, 2010.