This guide to pervasive developmental disorder (PDD) or autistic spectrum disorder (ASD) first provides a review of the literature on defining characteristics of PDD/ASD, causes of PDD, and diagnosis of PDD. Review of intervention and treatment comprises the major portion of the paper. After briefly considering parent education, this section examines behavioral interventions including positive behavioral support, applied behavior analysis, and pivotal response training. Therapeutic and educational interventions are discussed next and include floor time play therapy, occupational therapy, sensory integration therapy, speech therapy, social skills training, the Treatment and Education of Autistic and Related Handicapped Children program, and transitional planning. A discussion of major psychotropic interventions completes the section on intervention. The following section considers how PDD affects families. A final discussion notes that the literature review yielded inconclusive results regarding causality, although there is agreement that ineffective parenting does not cause PDD; that no diagnosis should be based on only one test; that there is agreement that early diagnosis and intervention produce more favorable outcomes; and that parents need to advocate for their children. Appendices include a sample of the Childhood Autism Scale and the Diagnostic Checklist for Behavior Disturbed Children, a sample Individualized Education Program, a list of resources, and case studies. (Contains 26 references.) (DB)