Purpose: This study examined the role of uncertainty and perceived control in predicting the communicative participation and mental health of adults who stutter. Method: Two hundred sixty-nine adults who stutter completed measures of uncertainty about stuttering, perceived control of stuttering, communicative participation, and global mental health. In addition, participants self-reported on a variety of demographic and speech-related measures. Correlational analyses and hierarchical regression were performed to determine associations between variables of interest. Results: Uncertainty accounted for significant variance in communicative participation and global mental health after statistically controlling for the effects of demographic and speech-related variables. Perceived control accounted for significant variance in communicative participation over and above what was accounted for by demographic variables, speech-related variables, and uncertainty. Conclusions: The findings suggest that uncertainty about stuttering and perceived control of stuttering should be accounted for during assessment and intervention with adults who stutter. Interventions that specifically target uncertainty and perceived control may be useful in improving therapeutic outcomes for individuals who stutter.