What makes a headmaster successful? And what does a successful headmaster do? This article presents some results from a research project - Successful school leadership in different school cultures - that aims to provide answers to these questions. The results derive from interviews, questionnaires, observations and pupils' essays, and comprise the criteria by which different parties involved in schools assess the success of headmasters. As with other research in this field, this article establishes that headmasters find themselves in tension fields that are constituted by the varied interests of the different parties involved in schools. These relationships are analysed with regard to three tension fields that affect Swedish schools today: between employer and employees; between pupils and adults; and between change and continuity. However, the work lives of headmasters isn't characterised by tensions only, but by alliances as well. Hence, headmasters' alliances with various other parties within the school are also analysed. These alliances are both a way of dealing with the tensions that headmasters meet on a daily basis, and a way of creating both success and a leadership based on the school culture. However, the general development trend that we find in Swedish schools, which lift the headmaster out of the school to become the last among superiors rather than the first among equals, constricts the latitude for more culture-specific school leadership.