PurposeLeaders' behavior has a critical impact on workers' safety behavior. However, previous studies have shown contradictive views on the effect of different leadership styles on safety behavior. One reason may be that the effectiveness of leaders' behavior varies according to diverse contexts. This study examines the effect of transformational and transactional leadership (TsL) on the safety behavior of on-site workers under different levels of social capital in construction projects.Design/methodology/approachSafety behavior is divided into three types: safety compliance (SC), organizational-oriented safety participation and individual-oriented safety participation (ISP). Questionnaire survey data were collected from 302 construction workers in the Chinese construction industry.FindingsThe results indicate that the positive effect of transformational leadership (TfL) of frontline supervisors on the two types of construction workers' safety participation is enhanced when social capital is high, although TfL has no significant effect on SC behavior. In contrast, TsL can promote construction workers' SC behavior and organizational-oriented safety participation and social capital positively moderating these relationships. TsL has no significant effect on ISP, but its interaction with safety behavior is positively related to ISP.Research limitations/implicationsThis study explains the inconsistent findings of previous research related to the role of leadership in safety behavior by introducing the social capitaltheory and distinguishing safety participation into two typesThis study is confined to one specific country, future research may benefit from investigating whether the conclusions of this study will be different in other nations with diverse cultures.Practical implicationsThe findings of the study provide frontline supervisors with new insights into improving workers' safety and the efficiency of leadership in safety management.Originality/valueThis study explains the inconsistent findings of previous research related to the role of leadership in safety behavior by introducing the social capital theory and distinguishing safety participation into two types.