Principals have an important function in schools’ ability to create high-quality learning and teaching. As the expectations placed on principals are high, large resources are invested in school leadership training, thus necessitating research on the impact of such initiatives. In this article, we report on a longitudinal research study on the training programme for principals in Sweden. The aim was to examine the programme’s impacts on the principals’ leadership and school organisations. We did this by interviewing principals, teachers and students at four schools during the principals’ participation in the programme. Giddens’s theory of structuration was used to analyse the study. The results showed that leadership needs to be foregrounded throughout the training and that awareness of the function of principals in leading schools’ structuration processes (i.e., their creation of meaning making) should be clarified.