The purpose of this report is to set forth policy options for supporting developing countries and transition economies in adapting their secondary education systems to demands arising from the successful expansion of primary education and the socioeconomic challenges presented by globalization and the knowledge-based economy. The report analyzes the key issues facing secondary education in the 21st century and, on the basis of global experience, presents a policy framework to guide decision makers in their efforts to transform and expand secondary education systems. It focuses on six main messages: (1) Secondary education has taken on a mission of its own, one that has the policy peculiarities of being at the same time terminal and preparatory, compulsory and postcompulsory, uniform and diverse; (2) Expanding equitable access and improving quality to ensure relevance are the twin challenges of secondary education worldwide; (3) In the context of the knowledge society, changing work patterns are leading to radically new approaches in the way curricular knowledge is selected, organized, and sequenced; (4) Qualified and motivated secondary school teachers are critical to the success of reforms of secondary education; (5) Multiple sources of funding and efficiency-enhancing measures should be considered to cover the significant financial investments required to expand access and improve the quality of secondary education; and (6) Traditional modes of state intervention and public management strategies need to be reformed in order to promote delivery of high-quality secondary education services. The following are appended: (1) Structure of Education Systems and Compulsory Education; (2) Grade Completion by Income Group and Gender, Selected Countries, Various Years; (3) Educational Attainment by Income Group and Gender, Selected Countries; (4) Selected Education Pyramids; (5) Gross Enrollment Rates and Educational Attainment by Income Level; (6) A Road Map of Teacher Competencies for a Knowledge-Based Secondary School; (7) Public-Private Partnerships for Secondary Education; (8) Formula Funding in Secondary Education: Country Examples; (9) Asymmetric Decentralization in Colombia and South Africa; and (10) World Bank Support for Secondary Education. A bibliography and index are also included. (Contains 30 boxes, 33 figures, 30 tables, and 21 notes.)