As part of a larger project to rethink the federal role in elementary and secondary education, the Center on Education Policy prepared this compendium, which summarizes the findings of major studies of the implementation and effects of the No Child Left Behind Act (NCLB) conducted by various organizations and agencies. The brief summaries are intended as a starting point to familiarize policymakers with the range of research available about NCLB. This edition of the compendium focuses primarily on studies of Title I of the Elementary and Secondary Education Act (ESEA) as amended by NCLB. Criteria for reported studies include: (1) Published in 2005 or later, after states, districts, and schools had become familiar with the law's requirements and implementation was underway; (2) National or regional scope with evidence from multiple states and/or school districts, rather than being focused on a single state or one or two districts; (3) Conducted by a research organization, government agency, university, national organization with a research division, or scholars with expertise in NCLB issues; (4) Based on data collected through well-established research methods rather than being primarily opinion pieces; (5) Focused on a significant policy issue or outcome of NCLB; and (6) Can be accessed free of charge, at least in summary form, on the Web. The report is divided into nine sections: (1) Accountability and related issues; (2) Achievement and related issues; (3) Curriculum and instruction; (4) Funding, costs, and capacity; (5) General implementation; (6) Reading First; (7) School improvement and restructuring; (8) Supplemental educational services and school choice; and (9) Teacher quality.