Purpose – Previous studies have often yielded mixed results in relation to the similar-to-me effect on extra-role behaviors. Based on social exchange theory, the purpose of this paper is to uncover the contribution of personality similarity to organizational citizenship behavior (OCB), a type of extra-role behaviors.

Design/methodology/approach – Questionnaire surveys were conducted in a multinational bank in Hong Kong. The participants were matched sample of 403 customer service representatives from 81 teams and their corresponding team supervisors.

Findings – Personality similarity to peers and supervisors had a positive impact on individual OCB (OCB-I) and organizational OCB (OCB-O), respectively, through better communication and social integration. Moreover, personality similarity to peers was related only to OCB-I, whereas personality similarity to supervisor was associated only with OCB-O.

Research limitations/implications – Subordinates perform different facets of OCB depending on the subjects they are similar to in terms of personality. Being similar to others could facilitate communication and social integration, which in turn promote OCB targeted at similar individuals. The importance of distinguishing the similarity effects of peers and supervisors separately as well as scrutinizing the effects of different forms of OCB warrants future research attention.

Practical implications – Managers can promote OCB by enhancing communication and social integration among employees and supervisors.

Social implications – As OCB enhances organizational effectiveness, the economic development of society in general will eventually benefit from having more effective organizations.

Originality/value – This study addresses the inconsistent findings of previous studies regarding the impact of similarity on OCB. It demonstrates the contribution of personality similarity to OCB beyond the confounding effects of judgment bias. It also advances theory by studying personality similarity to peers in addition to the commonly studied similarity to supervisors.