Chronic insomnia is a common health problem with substantial consequences in older adults. Cognitive behavioral treatments are efficacious but not widely available. The aim of this study was to test the efficacy of brief behavioral treatment for insomnia (BBTI) vs an information control (IC) condition. A total of 79 older adults (mean age, 71.7 years; 54 women [70%]) with chronic insomnia and common comorbidities were recruited from the community and 1 primary care clinic. Participants were randomly assigned to either BBTI, consisting of individualized behavioral instructions delivered in 2 intervention sessions and 2 telephone calls, or IC, consisting of printed educational material. Both interventions were delivered by a nurse clinician. The primary outcome was categorically defined treatment response at 4 weeks, based on sleep questionnaires and diaries. Secondary outcomes included self-report symptom and health measures, sleep diaries, actigraphy, and polysomnography. Categorically defined response (67% [n = 26] vs 25% [n = 10]; χ(2) = 13.8) (P < .001) and the proportion of participants without insomnia (55% [n = 21] vs 13% [n = 5]; χ(2) = 15.5) (P < .001) were significantly higher for BBTI than for IC. The number needed to treat was 2.4 for each outcome. No differential effects were found for subgroups according to hypnotic or antidepressant use, sleep apnea, or recruitment source. The BBTI produced significantly better outcomes in self-reported sleep and health (group × time interaction, F(5,73) = 5.99, P < .001), sleep diary (F(8,70) = 4.32, P < .001), and actigraphy (F(4,74) = 17.72, P < .001), but not polysomnography. Improvements were maintained at 6 months. We found that BBTI is a simple, efficacious, and durable intervention for chronic insomnia in older adults that has potential for dissemination across medical settings. clinicaltrials.gov Identifier: NCT00177203.