Intended for planners, administrators, and advocates of services to young handicapped children, the casebook is designed to create awareness of the key dimensions of interagency coordination; to describe practices that are replicable or adaptable to other settings and which may facilitate linkages; and to provide a framework for planning interagency efforts at local, regional, or statewide levels. The document is divided into two major sections. Section 1 (three chapters) contains the overview, theoretical base, and a framework for planning; Section 2 contains a series of detailed abstracts from eight selected HCEEP (Handicapped Children's Early Childhood Education Program) demonstration, outreach, and state planning projects. "A General Overview" by J. Roberts and R. Holland discusses some reasons for interagency coordination activities in the field of special education and uses examples of hierarchical and lateral coordination. Six phases for putting coordination into practice are outlined, and elements crucial for successful coordination activities are pointed out. Chapter 2, "Interagency Coordination for Young Handicapped Children" by J. Elder, discusses the advantages for coordination, examines its essential characteristics, describes roadblocks, considers some critical factors for coordination, and offers ideas for programs serving young handicapped children and their families. The third chapter ("A Framework for Planning" by M. Woodard, et al.) explores a general planning framework in three phases--preplanning, plan development, and plan implementation. Section 2 describes the following eight programs: Project SCOOTER for Hearing Impaired Children; Massachusetts State Implementation Grant; Family, Infant and Toddler Project; Williamsburg Area Child Development Resources, Inc.; Maine State Implementation Grant; Connecticut State Implementation Grant; Infant Stimulation/Mother Training Program; and Regional Demonstration Program for Preschool Handicapped Children. Program abstracts describe activities, the reasons for involvement, resources needed, positive outcomes, and failures. Appended materials include a chart of techniques for decision making, sample forms and letters, and a copy of an interagency agreement. (SW)