The major objectives of this social psychiatric research are to conduct an epidemiological study of the mental health needs of Alachua County, a Southeastern county in the throes of social change, and to evaluate the utilization of existing personnel and caretaking facilities. The epidemiologic investigation will include: (1) a comprehensive rates-under-treatment survey of general hospitals, psychiatric institutions, and physicians' and psychiatrists' practices; (2) a random sample of more than 2,000 of the 100,000 residents of the county, and (3) socio-anthropological analyses of the county, including in-depth studies of selected high- and low-pathology neighborhoods, as well as an analysis of the social organization of the county. From this research we are attempting to provide a model study- first, a descriptive model, second, an explanatory model, and ultimately, a mathematical model from which a probability design will emerge. It is anticipated that this three-fold model can be utilized by other counties in the Southeast to ascertain their mental health needs, to evaluate their services, and to increase the effectiveness of their health care system.