This report summarizes preliminary and exploratory research conducted by the Council of the Great City Schools and the American Institutes for Research on urban school systems participating in the Trial Urban District Assessment (TUDA) of the National Assessment of Educational Progress (NAEP). The study is one of the first large-scale analyses of urban NAEP trends, and the first to examine local instructional and organizational practices alongside changes in NAEP scale scores in the participating cities. This report is also preliminary in the sense that it attempts to lay out a framework for how NAEP data on the TUDA districts might be analyzed in the future as the number of participating cities grows and the amount of data expands. The purpose of this project was to identify urban school systems that are making academic progress and to examine possible factors in their improvement. The overarching goal was to identify variables that might be contributing to improvement in urban education across the nation and to explore what might be needed to accelerate those gains. The report also discusses broad lessons for the implementation of the common core state standards. This report wraps up with a short list of recommendations to urban school districts about what they might put into place based on the findings of this report and a set of conclusions about next steps. Appended are: (1) How NAEP Is Administered; (2) District Demographics, NAEP Trends, Funding, and Teachers; (3) NAEP Analysis Methodology; (4) Alignment Analysis Methodology; (5) Case Study Methodology and Protocol; (6) Atlanta Case Study; (7) Boston Case Study; (8) Charlotte-Mecklenburg Case Study; (9) Individuals Interviewed on Site Visits and Materials Reviewed; and (10) Research Advisory Panel and Research Team. Individual sections contain footnotes. (Contains 101 footnotes, 141 tables, and 30 figures.) [For related reports, see "Addendum to Pieces of the Puzzle: Recent Performance Trends of Urban Districts--A Closer Look at 2009 NAEP Results" (ED528219); and "Pieces of the Puzzle: Factors in the Improvement of Urban School Districts on the National Assessment of Educational Progress. Abstract" (ED528222).]