This study analyzes how prosocial values, organizational concern, and impression management motives to engage in OCB relate to dispositional and situational factors beyond major personality constructs. The sample consists of 192 employees in 15 service organizations in Chile. The results show that organizational concern and prosocial values, as good soldier motives, increase when individuals are more affectively committed to their organizations and decrease when they have a more external perceived locus of control and a higher power distance orientation in their relationship with their managers. Impression management, as a good actor motive, increases when individuals have a more external perceived locus of control and a higher power distance orientation in their relationship with their managers. These findings suggest that dispositional differences, together with the attachment that employees feel toward the organization, affect employees" motives to engage in OCB. This study also provides directions for future research and managerial implications. (C) 2014 Elsevier Inc. All rights reserved.