John Stuart Mill had strong sympathies with a liberal form of market socialism based on worker-owned and worker-managed firms. He thought that only very few government interventions were needed to trigger a peaceful and spontaneous transition to such an economic system. This article recapitulates his thesis and argument by focusing on his major workPrinciples of Political Economy, which is rather neglected by philosophers, especially in the German-speaking world. I will argue that Mill was too optimistic in his hope for a (...) spontaneous transition without government intervention. Since it is possible to reconstruct how Mill thought this transition would proceed, it is also possible to identify at what point the transition did not advance in the way envisioned by him, but was blocked by antagonistic forces. I will argue that this insight is not only of historical value, but still poses a serious problem for John Rawls’s theory of justice. Rawls follows Mill closely in his discussion of the proper economic system and he faces the same problem of transition. (shrink)