Background and Significance: Community Health Centers (CHCs) are the nation's largest and fastest growing network of primary care (PC) clinics. There are 1,200 CHCs that provide clinical services to 21 million Americans. Almost half (49%) of CHC patients live in rural areas, 72% live at or below the Federal Poverty Level (100%), 67% are racial/ethnic minorities, and 36% are uninsured. Nationally, over one million CHC patients are diagnosed with a psychiatric disorder and the need for mental health (MH) services is increasing exponentially, with a 547% increase in CHC patients with a psychiatric diagnosis between 2001 and 2012. CHCs located in rural areas face the greatest challenges to managing psychiatric disorders due to the lack of MH specialists on staff and weak linkages between CHCs and MH specialists in the community. Because rural, minority, low income CHC patients face insurmountable geographical, cultural and financial barriers to specialty MH care, many of their PC providers feel obligated, yet unprepared, to manage complex psychiatric disorders like posttraumatic stress disorder (PTSD) and Bipolar Disorder (BD). PTSD and BD are devastating psychiatric disorders that often go undetected and untreated in PC. Most patients do not receive effective specialty MH care for these problems and the care provided in PC settings is often poor and ineffective. Patients with PTSD and BD have significantly worse educational attainment, lower family, social, and occupational functioning, and significantly lower quality of life. Comparative effectiveness research is needed to guide policy makers about how to best manage the growing demand for MH services in CHCs.