The goal of the Veterans Health Study (VHS) was to extend the work of the Medical Outcomes Study (MOS) into the VA, by developing methodology for monitoring patient-based outcomes of care for use in ambulatory outpatient care. The principal objective of the VHS was developing valid and reliable measures to assess general health-related quality of life (HRQoL) and identifying the presence of selected health conditions, their severity, and their impact on HRQoL. In this article, we provide an overview of the historical context, framework, objectives, and applications of the VHS for the purpose of assessing the health outcomes of veteran patients. The VHS is a prospective observational study that has followed 2425 VA patients for up to 2 years. The patients were sampled from users of the Veterans Affairs (VA) ambulatory care system in the Boston area. The health conditions selected were hypertension, diabetes, chronic lung disease, osteoarthritis of the knee, chronic low-back pain, and alcohol-related problems. These conditions were chosen because they are both prevalent in the VA and have measurable impacts on HRQoL. One of the cornerstones of the VHS was the development of the Veterans SF-36, modified from the MOS SF-36 for use in veteran ambulatory populations. Other key accomplishments included the development of patient-based disease-specific measures of health and the establishment of methods and logistics for comprehensive health outcomes research in large health care systems such as the VA, using these patient-based measures. Selected measures developed in the VHS, eg, the Veterans SF-36, have been integrated into the VA outcomes measurement system. The scope of the VHS is unique; it resulted in the development of a broad range of patient-focused process and outcome measures, as well as methodologies for assessing large numbers of patients, that have been widely used in the VA outpatient health care system for monitoring health outcomes across the nation.