Rett syndrome (RTT) is associated with a range of serious neurodevelopmental consequences including severe communicative impairments. Currently, no evidence-based communication interventions exist for the population (Sigafoos et al., 2009). The purpose of the current study was to examine the effectiveness of functional assessment (FA) and functional communication training (FCT) methods for teaching 3 individuals (ages 15-47 years) with classic RTT novel communicative behaviors. Using single-case experimental designs, functional reinforcers were identified (FA) and each participant quickly learned to activate a voice-output switch to obtain a reinforcer (FCT). These results suggest that individuals with classic RTT can learn novel communicative responses, which has important implications for future intervention research.