SYSTEMS ANALYSIS CAN BE APPLIED TO THE PLANNING AND DELIVERY OF MENTAL HEALTH SERVICES. THE MODELS PRESENTED SHOW HOW A SYSTEMS APPROACH CAN BE USED TO ANSWER SOME OF THE KEY QUESTIONS IN PLANNING, ORGANIZING, AND EVALUATING MENTAL HEALTH SERVICE PROGRAMS. MODEL 1 APPROACHES THE TASK OF DEFINING AND CATEGORIZING MENTAL HEALTH AND RELATED PROBLEMS. PROBLEMS ARE GROUPED AS BEING POLITICALLY DEFINED, SOCIALLY OR CULTURALLY DEFINED, AND INDIVIDUALLY DEFINED. MODEL 2 ASSESSES RESOURCES. IT PERMITS TYPES OF PERSONNEL AND INSTITUTIONS THAT ARE AVAILABLE TO PROVIDE SERVICES TO BE CROSS-REFERENCED TO TYPES OF INTERVENTION AND/OR SERVICES. AN EXAMPLE OF AN INFORMATION SYSTEM THAT MAY BE USED TO DEVELOP DATA ON NEED FOR SERVICES IN TERMS OF "USER REQUIREMENTS," MODEL 3 IS A DIAGRAMMATIC REPRESENTATION OF THE FLOW OF INFORMATION IN A COUNTY-WIDE DATA BANK ON CURRENT USERS OF SERVICES. A SERIES OF CHARTS CONSTITUTE MODEL 4, WHICH ILLUSTRATES A METHOD FOR DETERMINING THE CRITICAL PATHWAY OF AN INDIVIDUAL THROUGH THE CARE-GIVING SYSTEM. THE LINKAGE AMONG AGENCIES AND THE CHANNELS ALONG WHICH PEOPLE ARE PROCESSED IS SHOWN IN MODEL 5. THE FINAL MODEL DEMONSTRATES HOW THE ELEMENTS IN A MULTI-SERVICE FACILITY ARE LINKED WITH ONE ANOTHER IN TERMS OF PEOPLE WHO COME FOR HELP. THIS PAPER WAS PRESENTED AT THE 45TH ANNUAL MEETING OF THE AMERICAN ORTHOPSYCHIATRIC ASSOCIATION (CHICAGO, MARCH 20-23, 1968). (CG)