The National High School Center's goal is to encourage researchers, policymakers, and practitioners at all levels to engage in comprehensive, systemic efforts to maximize attainment for all high school students, with a focus on those students who have been historically underserved. To this end, it has developed a framework that consists of eight core elements and provides a lens for mapping school, district, and state high school improvement efforts. The exercise of mapping should inform strategic planning and implementation efforts by illuminating the connections among elements, revealing strengths and gaps in current state and district policies, and highlighting the stakeholders who should be aware of and involved in future improvement efforts. This document offers descriptions of the eight elements of high school improvement: (1) Rigorous Curriculum and Instruction; (2) Teacher Effectiveness and Professional Growth; (3) Stakeholder Engagement; (4) Organization and Structure; (5) Assessment and Accountability; (6) Student and Family Involvement; (7) Effective Leadership; and (8) Sustainability.