Using a one-year longitudinal study of four components of organizational commitment (affective, normative, continuance–sacrifices, and continuance–alternatives) on a sample of employees from multiple organizations (N = 220), we examined the relationships of employee Big-Five personality traits to employee commitment components, and the mediating role of positive and negative affective states. Personality was measured at Time 1 while affective states and commitment components were measured at Time 2, while controlling for Time 1 commitment. Extraversion and agreeableness were positively related to affective, normative, and continuance–sacrifices commitments via enhanced positive affect. Agreeableness was also positively linked to affective commitment and negatively associated with continuance–alternatives commitment through reduced negative affect. Finally, neuroticism was negatively linked to affective commitment, and positively related to continuance–alternatives commitment, through increased negative affect. The implications of these findings for our understanding of personality–commitment linkages are discussed.