We evaluated sluggish cognitive tempo (SCT) symptoms in relation to personality as assessed via both the Reinforcement Sensitivity Theory (BIS/BAS) and Five Factor (Big 5) Model of personality. 3172 students from five universities completed psychopathology, BIS/BAS, and Big 5 measures. Correlations and path models with SCT, attention-deficit/hyperactivity disorder (ADHD) dimensions, and anxiety/depression in relation to personality were examined. SCT evidenced a different pattern of relations to adult personality than ADHD and anxiety/depression. SCT was significantly uniquely associated with higher BIS and Neuroticism, as well as higher BAS Fun-Seeking. SCT was uniquely associated with lower Extraversion and Conscientiousness. This study provides the first evidence linking SCT to adult personality and underscores the importance of differentiating SCT from both ADHD and anxiety/depression. (C) 2018 Elsevier Inc. All rights reserved.