Cognitive behavioral therapy for insomnia (CBT-I) is a group of strategies which includes sleep restriction, stimulus control therapy, relaxation training, cognitive therapy, and various combinations of those methods. Growing evidence from controlled clinical trials indicates that the majority of patients (70 to 80%) with persistent insomnia respond to CBT, and approximately half of them achieve clinical remission. CBT-I produces significant improvements of sleep-onset latency, wake after sleep onset, sleep efficiency, and sleep quality. These benefits are paralleled by reductions of daytime fatigue, improvement in psychological symptoms, and decreased usage of hypnotics. Changes in sleep patterns are well maintained after completing therapy. Treatment outcomes have been documented primarily with prospective sleep diaries; studies using polysomnography and actigraphy have also supported these results. Considering the results of current peer-reviewed research, CBT-I should be the first-line therapy for persistent insomnia. Despite strong evidence supporting its efficacy and effectiveness, CBT-I remains under utilized by health care practitioners. Increased application of evidence-based CBT-I therapies and their extension into primary medical practices should be highly effective and should be recommended in the future for better clinical management of insomnia-related disorders.