Swedish teachers are currently expected to become more involved in school improvement based on the findings of research. One of the main goals of this work is to develop practice in its own contexts. Teachers become involved in action and research or, in other words, the combination of practice and theory. A central issue in this work is whether professionals can develop practice in the light of their own knowledge and experience and, at the same time, in the light of theory and research. How can the two fields of knowledge (experience and science) be combined in practice? The article describes how action research has been developed in Sweden and how and why it has been used with pre-schoolteachers in the Goteborg area. (Contains 1 figure and 2 tables.)