In three devolved Australian school systems, for over 20 years, Australian researchers have been interested in understanding how successful school leaders lead schools that have a broad range of student and school outcomes that are above expectations. This paper draws upon findings from five Tasmanian, 18 Victorian, and one Northern Territory multiple-perspective case studies of successful primary, secondary, and special school principals. All cases are part of the International Successful School Principalship Project (ISSPP) and follow the methodologies of the ISSPP. At each school, data collected included interviews with the principal, senior teachers, teachers, students, parents, and school council members and document analysis. In addition, nine cases included observation of school activities, and two cases included a teacher survey. The cases reveal a complicated pattern of leadership activities by the principal and other school leaders that includes setting school directions, building positive cultures, developing supportive organisational structures, enhancing personal, professional, organisational, and community capacity, and developing networks, collaborations, partnerships, and stakeholder engagement. These areas of leadership action interact with school, staff, family, and broader contextual factors to develop outstanding teaching and learning that results in a wide array of positive student and school outcomes. Student outcomes include academic, extra-curricular, co-curricular, personal, and social areas. School outcomes include reputation, learning environment, resource allocation, community empowerment, and teacher quality areas. Successful school leadership is shown to be a complex endeavour, led by the principal but involving many and able to be sustained successfully over many years, leading to important and diverse student and school outcomes.