This article agues that ideological power plays an important role in education and that it is part of a general trend in policy and social sciences to underestimate ideological and overestimate the role of political and economic power. The article sketches a concept of power in general and especially of ideological power based primarily on the work of sociologists Anthony Giddens and Michael Mann. The role of ideological power is illustrated by discussing the recent trend towards flexible schooling. The emerging flexible school organisation was analysed in an empirical study of the most prominent Danish project of school development in recent years, the SKUB-project from 1998 to 2006. One school in particular, Hellerup School, was constructed and built as part of the project and it is aspects of this institution and its practices that are presented. The study shows that communication, methods of teaching, and techniques of discipline were changed compared to traditionally organised schools. What politicians, administrators, school leaders and teachers were primarily concerned about in developing the new school organisation was the ideological question about legitimacy: does this kind of school organisation and practice seem reasonable to students, parents, and public opinion, and is it in harmony with contemporary organisations in general? New ways of organising schools and the introduction of new frameworks do not necessarily result in reformed teaching practices. But in the case of SKUB and Hellerup they actually did so. The reason was that the new frameworks made possible methods of teaching that students accepted more readily than the traditional ones. Educational development is not only the result of political and economic powers but also of what seems reasonable to students, teachers, parents, and public opinion. Ideology matters in education. (Contains 2 notes.)