This report presents findings from a study of the ways in which interagency efforts by State and local government agencies influence accessibility of services for children with handicapping conditions and their families. The research was designed as a case study of a mid-Atlantic State that has a wide range of demographic characteristics. Thirty state personnel involved with planning or programs for children with handicaps and their families were interviewed, and information from documents and meetings was examined. The organizational conditions and interpersonal relationships that determine whether an interagency effort is cooperative, coordinative, or collaborative are described in terms of the following features: interagency objective, interagency policies, interagency structure, resources, loyalty to the interagency effort, procedures to establish agreement, decisionmaking processes, and roles of key personnel. Three state interagency committees were studied: the State Coordinating Council for Residential Placement, the Interagency Planning Committee for Children, and the Interagency Coordinating Council. The report concludes with a discussion of the implications of study findings for interagency efforts associated with Part H of Public Law 99-457. (Nine references) (JDD)