This research presents theoretical and empirical evidence to show the usefulness of a moderated mediation model to test individual differences in Behavioural Approach System in the prediction of workplace performance. We consider mastery approach orientation as the mediator in the relationship between Behavioural Approach System (BAS) and work performance. Additionally, we examined the moderated effect of a rewarding climate on the indirect effect of BAS in the prediction of work performance. Results from 123 supervisors’ ratings of employees’ work performance supported the model whereby the indirect effect of BAS on work performance via mastery orientation was strongest when the psychological climate of the organization was also rewarding. This model further advances our understanding of how individual differences in conjunction with contextual factors may influence work-related behaviour.