Although research has shown that safety leadership is a strong predictor of safety outcomes, it is unclear what factors lead to safety leadership. This unexplored area has hindered the development of effective interventions to promote safety leadership. This study addresses the knowledge gap by examining how job characteristics and personal resources influence construction leaders’ engagement in safety leadership based on the Job Demands-Resources (JD-R) model in positive psychology. An online survey was distributed to all managerial employees in a large U.S. construction organization, resulting in 383 valid responses. The structural equation modeling analysis indicates that job characteristics (social support, work autonomy and risk perception) and personal resources (psychological capital) significantly contribute to safety-specific transformational leadership through work engagement. Moreover, psychological capital moderates the effect of social support on leaders’ engagement in safety leadership. The implications of the present findings regarding safety leadership research are also discussed.