A psychiatric outcomes study that examined caseload attributes, patterns of treatment, and clinical outcomes in 950 adult outpatients was conducted as part of a Quality Improvement (QI) initiative in a large HMO. Patients were assessed pre- and post-treatment with measures of symptomatology (SCL-90) and functioning (SF-36), plus pre-treatment measures of personality disorder, comorbid problems, and sociodemographic variables. Significant improvements in psychological functioning and symptomatology were seen for 39-50% of patients, while 4-11% had significantly worsened. The study not only provided the HMO with useful baseline information on the performance of its psychiatric services, but also provided important lessons in how to conduct outcomes projects relevant to QI efforts. The study should be seen as part of an early effort of a large organization to move from a paradigm of Quality Assurance to one of Quality Improvement in the area of mental health.