The Anglo-Saxon countries have implemented Management by Objectives (MBO) complemented with school-based management (SBM) fairly rapidly. Although these countries are considered something of a benchmark of stability, research on principals reveals that they experience high levels of stress and that this is associated with poorer job performance. These findings raise the question of whether increased stress and poorer performance are the result of the new SBM role. In this article, empirical research on Sweden is used to address this question. While Sweden has not come as far as England in the implementation of SBM, it is farther along than other European countries. Paying specific attention to the SBM role, the article uses a qualitative method to describe the implementation of MBO in two cases with different characteristics, one centralized and one decentralized. A quantitative method is also used to conduct a large scale study of stress levels among all principals in upper secondary schools in Sweden. The results indicate that the choice of whether to retain the traditional principal role, developed at a time of centralized management by rules, or to replace it with a new SBM role influences the level of stress that principals experience, although in different ways. The practical implications of these findings are discussed in the final section of the paper.