The "No Child Left Behind Act of 2001 (NCLB)" is designed to achieve an ambitious goal: All children will be proficient in reading and mathematics by the 2013-14 school year. A key strategy for achieving this goal is accountability. Based on findings from two federally funded studies--the Study of State Implementation of Accountability and Teacher Quality Under "NCLB" (SSI-"NCLB") and the National Longitudinal Study of "NCLB" (NLS-"NCLB")--this report describes the progress that states, districts, and schools have made in implementing the accountability provisions of "NCLB" through 2006-07. Data were collected in state-level interviews; surveys of a nationally representative sample of district officials, principals, and teachers; surveys of parents in eight school districts; and surveys of supplemental educational service providers in 16 districts in 2004-05 and in 2006-07. This report is based on data collected in 2004-05 and 2006-07, and updates findings from the Interim report that were based on data collected in 2004-05. States used the flexibility provided by "NCLB" to establish accountability systems that varied in terms of the rigor of their academic standards, the level at which they set proficiency, the type of assessments they use, and the manner in which they calculated Adequate Yearly Progress (AYP) and set their annual proficiency targets. As a result of these differences as well as differences in student achievement, there was a large variation across states in the percentage of schools missing AYP and being identified for improvement. Appendices include: (1) Description of NLS-"NCLB" and SSI-"NCLB" Methodologies; (2) State Policy Tables; (3) Supplemental Exhibits; and (4) Standard Error Exhibits. (Contains 127 footnotes and 140 exhibits.) [This report was prepared for the Policy and Program Studies Service, Office of Planning, Evaluation and Policy Development, U.S. Department of Education.]