This study examines the relation between the prerequisites of principals in compulsory schools and to what extent they hence engage in instructional leadership. Three main questions are therefore posed which seek to describe how frequently the principals say that they engage in instructional leadership, how the principals say that their prerequisites are and to what extent these prerequisites affect their ability to be instructional leaders. A hypothesis is formulated that principals with favourable prerequisites are more likely to engage in an instructional leadership. To define instructional leadership Viviane Robinsons leadership dimensions ”planning, coordinating and evaluating teaching and the curriculum” and ”promoting participating in teacher learning and developement” are used as the foundation for the operationalisation of questions in the survey. The study finds that most of all the national principal education program affects the principals ability to be instructional leaders. Also the school managerand the municipal political board are important factors for the principals engagement in instructional leadership. Furthermore this study implicates that prerequisites, such as the number of employees or the time the principals say they have to be instructional leaders, have no, or almost no, effect on how frequently the principals engage in instructional leadership.