This paper outlines a case study based upon the functional assessment of a pre-school child's aggressive and disruptive behaviors, revealing difficulties with transitions from one activity to another at school. Antecedent conditions and functional communication were addressed in the behavior plan using a schedule board based on the Picture Exchange Communication System (PECS). After implementation of the PECS intervention, disruptive and aggressive behavior decreased dramatically with a concurrent increase in cooperative behavior. Appropriate behavior during transition times was maintained throughout the remainder of the school year. The case study provided illustrates the usefulness of a functional picture communication board and daily schedule for a young child with pervasive developmental disorder. (Contains 20 references and 2 figures.) (GCP)