A case study on the development of safety culture through learning processes.-Initially, when learning the trade of carpentry, and later on in life through practice at construction sites. In an action research part new accident prevention strategies were developed in cooperation with actors in a trade school and in three carpentry companies in relation to five construction sites. The project draws on organizational culture theories of symbolic interactionism and on practice based learning i communities of practice. The methodological approach is primarily ethnographic. Four different cultures, containing contrasting conceptions of accidents and prevention, existed side by side. However, elements of similar conceptions, especially concerning values of work characterize all the cultures. In the participative processes of developing new preventive strategies, it proved promising to emphasize the cultural elements, such as value on autonomy, fellow-feeling and cooperation. Furthermore, the project experienced most succes in developing prevention, when theory and practice of safety was integrated through dialogue and learning processes.