A model interdisciplinary diagnostic and treatment nursery program for developmentally disabled children is objectively described to enable documentation of effectiveness and replication. The major components of the program were the parent-professional partnership and the objective specification by the interdisciplinary team of problems, treatment plan, and treatment methods for each youngster. The concept of efficiency index is used to document and compare program effectiveness for four treatment cases, one of which is presented in detail. Reasons for program effectiveness and potential problem areas are discussed.