Previous research has not explored the Five Factor Model of personality among adults who stutter. Therefore, the present study investigated the five personality domains of Neuroticism, Extraversion, Openness, Agreeableness and Conscientiousness, as measured by the NEO Five Factor Inventory (NEO-FFI), in a sample of 93 adults seeking speech treatment for stuttering, and compared these scores with normative data from an Australian and a United States sample. Results revealed that NEO-FFI scores for the stuttering group were within the ‘average’ range for all five personality domains. However, adults who stutter were characterized by significantly higher Neuroticism, and significantly lower Agreeableness and Conscientiousness, than normative samples. No significant differences were found between groups on the dimensions of Extraversion and Openness. These results are discussed with reference to the relationship between personality factors among adults who stutter, their directionality, and implications for predicting treatment outcome.