Project Summary Stuttering is described as a multifactorial disorder that manifests as involuntary disruptions in the automatic, fluent planning and production of speech. Lifelong stuttering has a crippling impact on academic achievement, occupational success, and psychosocial wellness. Although early intervention can be successful to deter these negative outcomes, many children who receive treatment continue to stutter into adulthood. Unfortunately, many adults who stutter do not respond to treatment, and little is known about the mediating factors that many contribute to an individual client’s response to intervention. Recent advances in clinical and cognitive psychology have considered measures of executive function during initial assessment to account for some of the variability across heterogeneous, difficult-to-treat clients. Executive function is one potential moderating factor that has recently garnered theoretical and empirical interest relative to stuttering in children, who exhibit weaknesses in two critical but overlapping aspects of executive function: inhibition and working memory capacity. Adults who stutter also perform more poorly than non-stuttering adults during tasks that require efficient inhibition processes or rely on phonological working memory, suggesting that early executive function deficits remain a concern into adulthood and may serve as a sensitive predictor of success during treatment. Consideration of executive function may be of even greater importance to adults who stutter than children, as traditional and contemporary treatment approaches for older clients rely heavily on inhibitory control of (a) actions, thoughts, or emotions, and/or (b) maintaining new target behaviors in working memory. To date, however, the predictive value of executive function relative to clinical outcomes for adults who stutter remains overlooked. To address this critical gap, the proposed project will take the first steps in demonstrating the relevance of executive function to behaviors which underlie successful clinical intervention for fluency disorders. Specifically, this study will examine working memory in adults who do and do not stutter during inhibition of (1) speech and non-speech motor movements [Aim 1], (2) intrusive negative cognitions related to speech production [Aim 2], and (3) speech motor movement and negative cognitions related to speech production, simultaneously, similar to everyday speech production for adults who stutter [Aim 3]. These proposed experimental studies will establish important baseline data for future full-fledged clinical investigations of individual differences in executive function in adults who stutter, and examining how these differences may interact with specific treatment strategies.