Problem Statement – School leadership and the improvement of students’ outcomes became a concern for educational policies both in Portugal and internationally.

Purpose of the Study – This study aims to explore the relationship of school leadership exercised by Principals and students’ academic outcomes.

Methods – The study adopts mixed-methods, combining the analysis of national assessment and examination data sets, a questionnaire survey (LOLSO, Leithwood, Mulford & Silins, 2004), structured open-ended interviews and focus groups to the principals of 6 school groupings, heads of department, teachers and students. We use the structural equations model and the t-Student test to check the importance and influence of school factors on student outcomes and to assess the significance of the difference between the mean values of the different constructs.

Findings and Results – From the analysis of the results, we can conclude that there is an indirect influence of the Principal´s leadership practices on students’ outcomes. This influence is the result of school improvement processes and of the distribution of leadership amongst school teachers. School improvement creates conditions for teachers to develop their work and improve the quality of teaching, which has a positive and direct impact on learning and raises the level of students’ engagement in school. This is also accomplished through the influence of the Principal´s leadership practices on the work of teachers: directly or through the heads of department.

Keywords: Leadership, Principal, Students’ Outcomes, School improvement