Twenty-four older adults with persistent psychophysiological insomnia were randomly assigned to an immediate or a delayed cognitive-behavioral intervention in a waiting-list control group design. Cognitive-behavior therapy consisted of an 8-week group intervention aimed at changing maladaptive sleep habits and altering dysfunctional beliefs and attitudes about sleeplessness. Treatment was effective in reducing sleep latency, wake after sleep onset, and early morning awakening, and in increasing sleep efficiency. The magnitude of changes obtained on polysomnographic measures was smaller but in the same direction as that obtained on daily sleep diaries. Sleep improvements obtained by the immediate-treatment group were replicated with the delayed treatment condition. Therapeutic gains were well maintained at 3- and 12-month follow-ups. Clinical validation of outcome was obtained through collateral ratings from the patients and their significant others. The findings indicate that late-life insomnia can be effectively treated with nonpharmacological interventions.