This article describes an ICT-based and capability-driven model for assessing ICT in education capabilities and maturity of schools. The proposed model, called ICTE-MM (ICT in School Education Maturity Model), has three elements supporting educational processes: information criteria, ICT resources, and leverage domains. Changing the traditional and exclusive focus on ICT, five Leverage Domains are defined: Educational Management, Infrastructure, Administrators, Teachers and Students. The Leverage Domains generate a hierarchical structure with a second level named Key Domain Areas. These areas should be measurable and controllable, so they are related to a third hierarchical level, called Critical Variables, allowing the model's elements to be assessed qualitatively and quantitatively. The capability and maturity of these variables associated with the intersection with the other two elements establish five levels of capability. The proposed model is strongly supported by the international standards and best practices for ICT management. It has been validated through data collection instruments and its associated web-support tool was also refined with a small pilot study. In summary, the proposed ICTE-MM model provides a basis for self-assessment and improvement planning. It is not just a diagnostic tool but has also been found to be useful for guiding the principals in ICT investment.