Abstract Introduction Chronic pain is difficult to treat and often precedes or exacerbates sleep disturbances such as insomnia. Insomnia, in turn, can amplify the pain experience. Both conditions are associated with inflammatory processes, which may be involved in the bi-directional relationship between pain and sleep. Cognitive behavioral therapy (CBT) for pain and CBT for insomnia are evidence based interventions for, respectively, chronic pain and insomnia. The study objectives were to determine the feasibility of combining CBT for pain and for insomnia and to assess the effects of the combined intervention and the stand alone interventions on pain, sleep, and mood outcomes compared to a control condition. Methods Twenty-one adults with co-occurring chronic pain and chronic insomnia were randomized to either CBT for pain, CBT for insomnia, combined CBT for pain and insomnia, or a wait-list control condition. Results The combined CBT intervention was feasible to deliver and produced significant improvements in sleep, disability from pain, depression and fatigue compared to the control condition. Overall, the combined intervention appeared to have a strong advantage over CBT for pain on most outcomes, modest advantage over both CBT for insomnia in reducing insomnia severity in chronic pain patients. Discussion CBT for pain and CBT for insomnia may be combined with good results for patients with co-occurring chronic pain and insomnia.