The purpose of this study was to evaluate the effects of functional communication training (FCT) on the occurrence of non-targeted disruptive behavior. The 10 participants were preschool-aged children with developmental disabilities who engaged in both destructive (property destruction, aggression, self-injury) and disruptive (hand flapping, spinning in circles, shrill laughter, screaming, crying) behaviors. Only destructive behavior was targeted for the functional analyses and FCT, but data were also collected on disruptive behaviors. All procedures were conducted in the participants' homes by their mothers with investigator coaching. Phase 1 consisted of conducting a functional analysis within a multielement design. Phase 2 consisted of conducting FCT with demand fading and repeated extinction baselines within a reversal design. Single-case data are provided for 3 participants, and summary data are provided for all 10 participants. Results of phase 1 showed that all participants' destructive and disruptive behavior was maintained, at least in part, by negative reinforcement. Results of phase 2 showed that both destructive behavior and non-targeted disruptive behavior occurred at lower levels during FCT when compared to the functional analysis demand condition and baseline conditions, suggesting that FCT was effective in decreasing both target destructive behavior and non-targeted disruptive behaviors.