THERE IS A SIGNIFICANT TREND TOWARD BUILDING COMPREHENSIVE, ACCOUNTABLE, AND PRODUCTIVE HUMAN SERVICE SYSTEMS AT THE COMMUNITY OR REGIONAL LEVEL. THE HUMAN ECOLOGY INSTITUTE HAS SUPPORTED THIS TREND THROUGH TRAINING, TECHNICAL ASSISTANCE, EVALUATION, DOCUMENTATION OF HUMAN SERVICE SYSTEM TECHNOLOGY, AND THE DEVELOPMENT AND IMPLEMENTATION OF TOTAL SYSTEMS IN COMMUNITIES AND SUBSTATE REGIONS. IN 1971, THE INSTITUTE WAS ASKED BY DHEW TO CONTRIBUTE A SYSTEM PERSPECTIVE TO THE SITO PROGRAM. IN WHAT HAS COME TO BE CALLED THE 'LOOP MODEL' OF AN OPERATING HUMAN SERVICE SYSTEM, THE FOLLOWING SEVEN KEY ELEMENTS WERE IDENTIFIED AS FORMING THE CONTEXT OF AN ACCOUNTABLE AND PRODUCTIVE SYSTEM: A SET OF COMMUNITY MEMBERS TO BE SERVED BY THE SYSTEM; SYSTEM GOVERNANCE; SYSTEM MANAGER; SERVICE DELIVERY SYSTEM; AUDIT OF ACHIEVED EFFECTS; AND FUNDING OF THE OPERATING SYSTEM. THE DEVELOPMENT PROCESS IN DEFINING THE SYSTEM PERSPECTIVE INVOLVED SYSTEM INITIATION, SYSTEM DEFINITION AND DESIGN, PILOT TESTING, SYSTEM ACQUISITION (FABRICATION AND INSTALLATION), AND TRIAL OPERATIONS. LESSONS LEARNED FROM THE SITO PROGRAM ARE EXAMINED: THE MESSAGE IS THAT THE DEVELOPMENT OF COMPREHENSIVE, COMMUNITY-BASED MANAGEMENT, PLANNING, AND DELIVERY SYSTEMS STILL SEEM TO BE THE MOST LOGICAL WAY TO PROVIDE SERVICES, AND IMPROVEMENT IN SYSTEM DEVELOPMENT CAN AND SHOULD BE MADE. ALL ILLUSTRATION OF A HUMAN SERVICE SYSTEM IN THE COMMUNITY CONTEXT IS PRESENTED. (DEP)