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. (Contains 5 tables.)