The reactivity of self-monitoring procedures with retarded adolescents was investigated using single-case designs. The effects of 2 variables, social reinforcement and feedback, on the degree of reactivity were also examined. Both subjects monitored a socially undesirable behavior and were asked to self-record for extended periods of time with minimal cues from the environment. Self-monitoring produced reactive decreases in the target behavior. Reinforcement had a differential effect across subjects, further altering the target behavior for only 1 subject. Feedback decreased the behavior for the 2nd subject. The subjects'' accuracy in self-recording was quite low.