This report seeks to define basic terms for use in mental health, alcoholism, drug abuse and mental retardation programs in order to achieve some progress toward a long-range goal of improved communication and exchange of information among concerned disciplines in these fields. While the report does represent the most complete and developed work in this area to date, the NIMH does not require the use of these definitions in any particular program and does not necessarily endorse each of the definitions in the report. The document focuses on the need for definitions, the ways in which organizations provide services, the nature of the recipients of such services, the purpose of the services offered, and the costs and revenues incurred in rendering services. Hopefully, wider distribution and discussion of this report will lead to improved communication and continued development of a more defined set of definitions. (Author/PC)