This work proposed a theoretical model for investigating the process of job performance (JP) and organizational commitment (OC) using career stage as a moderator. In the proposed model, OC and leader-member exchange (LMX) directly influence JP, while LMX and job satisfaction (JS) indirectly influence JP via the mediation of OC. The causal relationships are moderated by a career stage moderator, which combines age and employee tenure. The moderating effects were simultaneously tested using data from high-tech personnel in a large Taiwanese manufacturer. The extent to which OC affects JP is similar for the initial and mature stage groups, while the influences of LMX on both OC and JP are stronger for mature stage individuals than initial stage individuals. Finally, JS influences OC more strongly for initial stage individuals than mature stage individuals. The implications of the above findings are discussed.