The DIAMOND Study evaluates the effects of a statewide change in reimbursement combined with facilitated implementation of a best practice primary care based collaborative care approach involving the primary care physician, a care manager and close psychiatry consultation. The Institute for Clinical Systems Improvement (ICSI) is facilitating the DIAMOND Initiative training and implementation support for 26 medical groups to implement best practice in a staggered implementation that began in the spring of 2008. The participating health plans pay ICSI-certified medical groups a monthly fee for DIAMOND services. The DIAMOND Study, funded by a grant from the National Institute of Mental Health (NIMH), is designed to achieve the following aims: (1) To use a multiple baseline design with staggered implementation to test the effect of these changes on the frequency and sustainability of evidence-based care processes for patients with depression; (2) To test the effect of the care process changes on change in depression symptoms, healthcare costs, and work productivity; (3) To identify the organizational factors within a recent conceptual model that affect the implementation and effects of the care changes; (4) To describe the reach, adverse outcomes, adoption, implementation, maintenance, and spread of the system changes and new care processes in order to evaluate their potential for broad replication The baseline results of patient surveys found that 68% of patients have been sad/depressed most of the past 2 yrs, 65% have been treated for depression in the past, of these, most were treat 2+ times, have been absent from work an avg of 3 hrs/wk, and 12 hrs/wk of low productivity. The baseline results of medical group surveys found that most medical groups reported no key depression management systems present and working well. The highest rate reported was a system to assure use of specific depression codes, which 22% of clinics reported present and working well.