Background: Insomnia is a common and debilitating disorder experienced by up to 60% of cancer survivors. We evaluated the effectiveness of acupuncture versus cognitive behavior therapy for insomnia (CBT-I). Methods: We conducted a randomized clinical trial of acupuncture vs. CBT-I among 160 post-treatment cancer survivors with clinically diagnosed insomnia disorder. Acupuncture involved stimulating body points with needles. CBT-I included sleep restriction, stimulus control, cognitive restructuring, relaxation training, and education. The intervention duration was eight weeks (primary end point) with a follow up assessment at 20 weeks. Insomnia severity, measured by the Insomnia Severity Index, was the primary outcome. Results: The mean age of participants was 61.5 years, 57% (n = 91) were women, and 29.4% (n = 47) were non-white. At the end of treatment, acupuncture reduced insomnia severity by 8.3 points (95% CI 7.3-9.4), compared to 10.9 points (95% CI 9.8-12.0) for CBT-I, with CBT-I being the more effective treatment overall (2.6, 95% CI 1.1 – 4.1, P = 0.0007). Patients with mild insomnia were significantly more likely to respond to CBT-I than acupuncture (85% vs. 18%, p < 0.0001); however, patients with moderate to severe insomnia had similar response rates to CBT-I and acupuncture (75% vs. 66%, p = 0.26). Both groups had few mild adverse events and maintained improvements up to 20 weeks. Both groups also had similar improvement in quality of life in physical health (p = 0.46) and mental health (p = 0.44) during the study. Conclusions: While both acupuncture and CBT-I resulted in clinically meaningful and durable effects among cancer survivors with insomnia, CBT-I was more effective, especially among patients with mild insomnia symptoms. Patients and oncology clinicians can use these findings to inform their choice of insomnia treatment. Clinical trial information: NCT02356575