An ecological model for service and advocacy for handicapped children through a residential diagnostic center is presented. Such a model is explained to provide a meaningful interrelationship of varied resources and agencies at the local, state, and federal level with a focus on the generic program. Four positive interfacing functions relating to parent problems (such as lack of understanding about the child's handicap and inadequate knowledge upon which to base decisions) are discussed. Five basic service phases (referral, admission, diagnosis, planning and implementation) are described, and a case study is provided to illustrate the model's operation. Among other services ascribed to the ecologically oriented agency are workshops for parents and mediation between families and agencies. (CL)