Oppositional defiant disorder (ODD) is conceptualized as a disorder of negative affect and low effortful control. Yet empirical tests of trait associations with ODD remain limited. The current study examined the relationship between temperament and personality traits and Diagnostic and Statistical Manual of Mental Disorders (5th ed.) ODD symptom domains and related impairment in a preschool-age sample. Participants were 109 children ages 3-6 (59% male), overrecruited for ODD from the community, and their primary caregivers (87% mothers). ODD symptoms and impairment were measured using the Kiddie-Disruptive Behavior Disorder Schedule, temperament traits were measured using parent report on the Child Behavior Questionnaire and the Laboratory Temperament Assessment Battery, and personality traits were measured using examiner report on the California Child Q-Sort. Results suggest that high negative affect was associated with all three ODD symptom domains, whereas low agreeableness was specifically associated with the angry/irritable ODD symptom domain, and high surgency was associated with the argumentative/defiant and vindictive ODD symptom domains. Negative affect and surgency interacted with agreeableness to predict impairment, but not symptoms: Low agreeableness was associated with high impairment, regardless of other trait levels, whereas high negative affect and high surgency predicted high impairment in the presence of high agreeableness. Overall, results suggest ODD is a disorder of high negative affect. Furthermore, low agreeableness is differentially associated with affective ODD symptoms, and high surgency is associated with behavioral ODD symptoms. These traits interact in complex ways to predict impairment. Therefore, negative affect, agreeableness, and surgency may be useful early markers of ODD symptoms and impairment.