Increased opioid prescribing for chronic pain that is not due to cancer has been accompanied by large increases in abuse and overdose of prescription opioids. This paper describes how Group Health, a Seattle-based nonprofit health care system, implemented a major initiative to make opioid prescribing safer. In the initiative's first nine months, clinicians developed documented care plans for almost 6,000 patients receiving long-term opioid therapy for chronic pain. Evaluation of the initiative's effects on care processes and trends in adverse events is under way.