With the dramatic changes that are occurring in mental health and substance abuse treatment systems, it is imperative that the field keep its focus on the patient and the patient's outcomes of care. Outcomes management systems that measure the processes of care, the patient's characteristics, and the patient's outcomes of care can be helpful in maintaining this focus. To facilitate the development of these systems, the Outcomes Roundtable, a group of mental health consumer, professional, service, and policy-making organizations, has articulated a set of 12 broadly applicable principles of outcomes assessment. The principles call for outcomes assessments that are appropriate to the question being answered, that use tools with demonstrated validity and reliability and sensitivity to clinically important changes over time, and that always include the consumer perspective. In addition, the principles recommend outcomes assessments that create minimal burden for respondents and are adaptable to different health care systems, that include general health status as well as mental health status, and that include consumers' evaluation of treatment and outcomes. Outcomes assessment tools should quantify the type and extent of treatment, should include generic and disorder-specific information, and should measure areas of personal functioning affected by the disorder. Outcomes should be reassessed at clinically meaningful points in time. Outcomes assessment should use appropriate scientific design and representative samples and should examine outcomes of consumers who prematurely leave treatment as well as those who continue in treatment.