We propose to collaborate with AHCPR and other sites to demonstrate methods to evaluate strategies for implementing clinical guidelines in large group practices. Using existing databases and ongoing surveys, we have the capacity to inexpensively identify large samples of patients with diagnosed hypertension (HPT) and with diagnosed and undiagnosed depression (DPR), and to link them to their personal physicians. We will conduct one randomized controlled trial to evaluate guideline implementation strategies for HPT, and a second randomized trial for DPR guidelines, as applied by a large pre-paid group practice. In each study, we will assign each primary care provider in the Northwest Permanente medical group to a control condition or to one of three implementation strategies: Continuous Quality Improvement (CQI); Academic Detailing (AD); or CQI and AD combined. We will measure experimental effects primarily through changes in patients, health status, medical care, and cost of care. We will ascertain patient effects from medical records, clinical databases, accounting records, an ongoing medical visit survey, and a special follow-up survey. Our primary outcome measures will be change in blood pressure for HPT and the Beck Depression Inventory for DPR. At the conclusion of the study, we will survey physician knowledge and satisfaction. In addition, we will describe and explain guideline adoption and implementation processes, using a case study approach.