Are lean production jobs intrinsically motivating? More than 20 years after the arrival of lean production, this question remains unresolved. Generally accepted models of job design such as the Job Characteristics Model (JCM, (Hackman, J.R., Oldham, G.R. 1976. Motivation through the design of work: test of a theory. Organizational Behavior and Human Performance 16, 250?279.)) cannot explain the occurrence of worker intrinsic motivation in the context of lean production. In this paper, we extend the JCM to the lean production context to explain the theoretical relationship between job characteristics and motivational outcomes in lean production. We suggest that a configuration of lean production practices is more important for worker intrinsic motivation than are independent main effects, and that motivation may be limited by excessive leanness. We conclude that lean production job design may engender worker intrinsic motivation; however, there are likely to be substantial differences in intrinsic motivation under differing lean production configurations.