Depression is a prevalent, often chronic condition that has enormous personal, social, and financial consequences. Although technologies for treating depression have advanced notably over the past 20 years, many people continue to suffer needlessly, due in part to the lack of evidence-based treatment applied in primary care settings. Substantial public and private efforts have been devoted to encouraging individuals to seek care, improving recognition and diagnosis by primary care physicians, and implementing evidence-based treatment practices. From these efforts have come new models of care as well as an awareness of the critical barriers impeding clinical, organizational, economic, and policy implementation of effective care strategies. In this paper, we describe these clinical and systems barriers and consider the perspectives of various stakeholder groups; present emerging clinical models for providing evidence-based care as well as economic strategies for overcoming barriers to their implementation; and propose community-based approaches that will need to be tested. To achieve maximum benefits from current knowledge, we will need to implement a multi-level strategy employing focused efforts involving patients, providers, practice settings, health plans, purchasers (public and private), and populations (or communities): the '6 P' strategy.