When and why conscientious employees are proactive: A three-wave investigation on employees' conscientiousness and organizational proactive behavior

•Three-wave and Multi-source data were collected to examine the hypotheses.•Employee flourishing mediates the effect of conscientiousness on organizational proactive behavior (OPB).•Job meaningfulness (JM) moderates the conscientiousness-flourishing relationship.•JM moderates the indirect effect between conscientiousness and OPB via flourishing. This study investigates the mediating and moderating processes underlying conscientiousness and organizational proactive behavior from broaden-and-build theory. Using three-wave and multi-source data among 217 Chinese employees, this study found that flourishing mediated the relationship between conscientiousness and organizational proactive behavior. Moreover, job meaningfulness strengthens the relationship between conscientiousness and flourishing, as well as the mediation of flourishing between conscientiousness and organizational proactive behavior. The theoretical and managerial implications are further discussed.