This study explores the influence that different dimensions of workplace friendship cast on organizational citizenship behavior (OCB). I draw on social exchange theory, impression management theory, and affect theory to argue that workplace friendship opportunity (WFO) will lead to OCBO (OCB directed at the organization) through perceived organizational support (POS), and OCBI (OCB directed at individuals) through employees’ impression management tactics (IM). I also propose that workplace friendship prevalence (WFP) can lead to both OCBI and OCBO through positive affect (PA), with workplace friendship quality (WFQ) moderating these relations. The sample for this study includes 400 Concordia undergraduate business students, who are employed in various industries in Canada. Regression analyses were applied to analyze proposed mediation and moderated mediation relationships. Consistent with our hypotheses, we found that WFO is positively related to OCBO and OCBI, with POS and IM partially mediating these relationships, respectively. We also found that WFP is positively related to OCBI, but not OCBO. In contrast to the hypotheses, WFQ does not moderate the relationship between WFP and positive affect, and positive affect does not mediate the relation between WFP and OCBO/I. Post-hoc analyses indicate that WFQ is positively related to both OCBO and OCBI, and that the relationship between WFQ and OCBO is fully mediated by PA and the relationship between WFQ and OCBI is partially mediated by PA. Based on these results, companies can benefit from creating more friendship opportunity at work and promoting high friendship quality among employees. Considering that our sample is mostly young and they are university students, these results may be most applicable to organizations who have hired, or who intend to hire, young professionals from the millennial generation.