Social information processing and social learning theories were utilized to hypothesize that an employee's organizational citizenship behavior (OCB) is influenced by the collective OCB in one's workgroup. An aggregate measure of OCB was constructed based upon Podsakoff, MacKenzie, and Fetter's (1993) measures of Organ's (1988) typology of OCB, and the study was replicated using both supervisor and employee-provided ratings of OCB. The sample for this study included 566 employees (488 for the supervisor-rated analysis) from 56 workgroups in a manufacturing organization. The mean level of OCB for other members of one's workgroup explained significant variance in individual levels of OCB. We also found that this effect is moderated by the consistency of the display of the OCB within the workgroup. The consistency of OCB across coworkers was associated with more OCB by individuals and this effect was replicated across both supervisor and employee ratings. Explanations and uses for our findings are discussed.