A model is presented that estimates the rates, numbers, and socio-demographic characteristics of potential clientele for substance abuse programs. Using the synthetic estimates technique and existing bodies of information, the model has been tested and cross validated with substance abuse related problem indicators across the counties of Oregon with good results. The model has both strengths and weaknesses and may be seen as being of greatest value to policymakers, planning agencies, and program administrators in the field of substance abuse and related service programs.