In recent years, school management systems have become an important tool for effective e-leadership and data-based decision making. School management systems emphasize information flow and e-communication between teachers, students and parents. This study examines e-leadership by secondary-school principals through the Mashov school management system, implemented in 500 Israeli schools in order to increase school effectiveness. Semistructured interviews were conducted at the end of academic year 2010/2011 with 10 participants: eight secondary-school principals, a Ministry of Education supervisor, and a director of the school principals' training program. The results indicate that the system provides extensive support for school principals in managing the organization, delegating responsibilities and promoting e-leadership by teaching staff and, consequently, increases the pedagogical effectiveness of their school. e-Leadership through the school management system changes the entire school culture. It includes making data-based decisions; monitoring curriculum implementation and learning performance; interacting with teachers, students and parents; improving the school climate; and raising the level of student and parental involvement. The results are discussed in terms of the islands-of-innovation and comprehensive-innovation models of technology implementation. In order to enhance e-leadership, we recommend that school principals expand the implementation of school management systems among students and parents, delegate e-leadership responsibilities and monitor the level of teacher activity within the system.