This paper describes the behavioral treatment of acute onset school refusal in a 5-year old girl with Separation Anxiety Disorder (SAD). A functional classification was used to select a treatment approach that involved the parent and teacher using shaping, positive reinforcement and extinction. Results showed that by the end of the fifth week of treatment, the child was attending full time schooling and no longer met the criteria for SAD. Treatment gains were maintained at 4 and 12-month follow-ups. Results are discussed in terms of the efficacy of the treatment, the involvement of teachers and parents, and the treatment utility of a functional classification.