This chapter takes a macro-social view to summarize scholarship that describes organizations and systems of mental health care. Macro-social theories and research analyzing relationships among groups of health providers have shown that health care organizations, including mental health providers, are increasingly structured into social systems and interorganizational networks. The chapter summarizes research on social groups at a wider level of abstraction, showing how mental health care is provided by organizations working and evolving together within systems of care. Health care networks create systems and develop local health authorities, but some organizations and systems may still lack incentives to be cost efficient. Institutional theory examines the influence of institutional environments on the structure, function, and adaptation of organizations within organizational fields. Like medical care generally, mental health care is provided by organizations that work within formal and informal social networks.