Use of client records and census data as a research methodology can provide mental health planners with information on community needs as well as the adequacy of existing programs. Three ways of analyzing client records in conjunction with census data are: (1) tract by tract, comparing client geographic distribution with census characteristics; (2) client by tract, comparing demographic characteristics of clients with those of the general population in census tracts and the catchment area; and (3) client by client, comparing characteristics of client subpopulations. Examples based on three years of client records for a community mental health center demonstrated the uses of these analyses by showing that census areas characterized by high proportions of disenfranchised groups (e.g., divorced, low status, Spanish heritage) were high service utilizers; higher proportions of divorced, high school educated, and unemployed residents utilized services more than expected by population estimates; and dropouts from therapy could be indicated by demographic differences in marital status, income level, employment status, educational level, ethnicity, and previous mental health treatment. (Author/MH)