The paper argues that a distinction should be drawn between the Japanese Model and Lean Production. The first refers to the sum of social and cultural aspects of the Japanese traditional way of managing human resourses, whereas the second refers to the rather recent achievement of Continuous Improvement, elimination of waste and implementation of Just-In-Time (JIT). This distinction makes it possible to raise the question of the “exportability” of Lean Production outside Japan.The paper then examines three main sources of ambiguity outlined in the current debate on Lean Production: whether work becomes only harder or also smarter; whether JIT requires workers to be totally subordinated to the production needs, or whether it also depends on the workers willingness to participate; whether Lean Production should only be considered as a consequence of the Japanese workers’ defeat in the ’50s, or also as a selective acceptance by the Japanese management of some demands put forward by the Japanese workers’ movement.Some problems related to a successful implementation of Lean Production in Western countries are discussed in the final part of the article.