A 7-yr-old boy was reported by school officials and his mother to exhibit chronic fecal soiling (encopresis). A reinforcer sampling procedure was used to expose the boy to potential reinforcers to be used in a home-based motivation system. The mother provided instructions which served to make explicit a contingency between appropriate toileting and reinforcement. Within 10 days fecal soiling was eliminated, and a token system was added to maintain this positive change. An 11-month follow-up indicated no evidence of remission or symptom substitution. Pre- and post-psychodiagnostic evaluations were at variance with the child's behavior.