Federal mandates embodied in P.L. 99-457 require that professionals have the expertise to provide family-centered early intervention services, particularly developmental assessment. Written for psychologists, ASSESSMENT FOR EARLY INTERVENTION is a self-instructional guidebook relevant to all professionals who must acquire the unique perspectives and best practices to work with families and their infants and preschoolers with developmental disabilites.The ultimate purpose of early childhood assessment is the planning of programs for children and their families, and this guidebook emphasizes that flexible collaboration is a means to this end. It demonstrates how teams of parents and professionals can strive to make joint decisions about current and changing treatment needs. It also stresses that the assessor's competence in decision-making is more important to the process than the qualities of various assessment instruments. With content that is immediately applicable, ASSESSMENT FOR EARLY INTERVENTION moves beyond diagnosis (which is often premature) to prescribe broad interventions for improving the quality of life for the child and the family.