Temporary workers make up a sizeable part of the labor force in many countries and typically receive wages that are significantly lower than their permanent counterparts. This paper uses an efficiency wage model to explain the wage gap between temporary and permanent workers. High-performing temporary workers may gain promotion to permanent status, and a high wage to permanent workers therefore serves a dual purpose: it affects the effort of both permanent and temporary workers. Applying the model to the Korean experience, we discuss the effects of the labor market reforms in 1998 on inequality.