This study investigated the reciprocal relationship between perceptions of psychological contract fulfilment and employee performance (sales made and sales targets), and whether this was moderated by the quality and length of the social exchange relationship captured, respectively, through perceived organizational support (POS) and organizational tenure. We used a sample of 146 sales advisors and a four-point longitudinal design and found support for reciprocal links where performance predicted subsequent psychological contract fulfilment and vice versa. The strength of the relationship between performance and psychological contract fulfilment increased over time. The quality of the social exchange relationship (i.e., POS) moderated reciprocal links between sales made and sales targets met and perceptions of psychological contract fulfilment at earlier, but not later, time points. One way to interpret the findings is the changing nature of the unfolding relationship between support, psychological contract fulfilment, and performance, where a supportive relationship buffers failing to deliver at earlier time points, but at later time points employee performance and psychological contract fulfilment associate more strongly as both parties prioritize delivery.