The present and Nielsen's abstracts argue that change and learning are two related aspects of praxis. The present abstract will investigate the relation between developing praxis and its organization, while Nielsen's abstract will investigate the relation between learning and changing praxis. The presentation will discuss and analyse some empirical material from a project on conflictual cooperation in the building business. The analysis opens an opportunity to discuss and expand Lave and Wenger's notion of situated learning. The authors' original intention of understanding learning as an integral and inseparable aspect of social practice which is itself in motion, will be stressed. In a university dormitory we shall follow the construction of the shafts for the technical installations of the building. We shall see how the arrangements of professional work form planning as something to take place in one phase and to be followed in others. However, upcoming events make it necessary to continuously reorganize praxis, and the underspecification of drawings and plans makes it necessary to understand their meaning to modify the elements of the house accordingly. In this way our anticipatory production of the house leaves traces which we must take into account in our ensuing acts. Additionally it will be argued that the professionals may constitute different communities on the building site. This does not mean that the building site is a community of practice, all the same the conflictual cooperation and the contradictions in practice will open up possibilites for conflicts and learning which may or may not be realised by oldtimers as well as newcomers.