The University of North Dakota requests funds for a 27,883 square foot Northern Plains Center for Behavioral Research (NPCBR). It will house research and research training that focuses on mental disorders and behaviorally mediated diseases central to improving the health status of American Indians, the rural elderly poor, Latino migrant farmworkers, women, and children. They suffer disproportionate rates of depression, suicide, other serious mental disorders, and physical disorders such as diabetes and disorders of pregnancy that respond to behavioral treatment. There are extreme shortages of behavioral health researchers serving these groups. We propose the interdisciplinary training of researchers in nursing and psychology to address these critical unmet national public health needs. Active and pending PHS-funded studies include the cognitive effects of chronic pesticide exposure on children, and the role of nutrition in mitigating diabetes, cognitive decline among the elderly, and cholelithiasis among American Indian women. Our portfolio cannot be expanded and additional American Indian investigators trained without the specialized research facilities requested. Present facilities are improvised, substandard, or absent. We cannot assist these most vulnerable groups without appropriate space. Local funding is unavailable. Action is urgent since the Northern Plains American Indian population will double during the next 15 years; the region is rapidly aging and significantly older than the Nation as a whole. NPCBR proposes a 20-year plan to serve these groups. It builds on our leadership in training research-competent American Indian nurses and psychologists. To continue our service to vulnerable populations, funding the NPCBR is essential.