Town planning is often seen as an instrument of social reform. It is argued here that this was not the case under social democracy, and by implication neo-liberalism and globalization do not necessarily act as brakes upon reform. Planning should be interpreted in class terms, as a means of stabilization and legitimation thereby helping to ensure growth. It fragments social reality in order to contain the political movements that urban problems could generate. This view of planning may explain why social reform is not high on planning's agenda. But social reform is possible but only at times of intense conflict. For planning to take advantage of such transient opportunities, planning theory needs development. The paper concludes by developing a model of social reform and looking at some of the flashpoints that could trigger it.