Reinforcement menus were used to dhange response probabilities while maintaining control over two ''trainable," female, mentally retarded children. An empirically determined reinforcement menu representing high probability behaviors, five for S1 and four for S2, was used in a contingency management system. Instructions were given concerning the contingencies for obtaining reinforcement. Subjects were allowed the opportunity to engage in a high probability behavior only after successful completion of fixed units of reading or arithmetic tasks. After stable performance was established, four additional menus were prepared to approximate in increasing degree, low probability behavior. Measurements were taken of task time and response duration, the time spent traveling to and from the reinforcement area. Task time and response duration reached asymptotic values and remained at baseline values throughout the menu fading procedures. At the completion of the menu fading, subjects were doing units of work involving reading and mathematics in order to have the opportunity to do some reinforcing arithmetic.