For most of the past decade, the Chicago Public Schools have received significant support from the Bill and Melinda Gates Foundation to improve the performance of city high schools. As part of that support, the Foundation contracted with SRI International and the Consortium on Chicago School Research to conduct a comprehensive evaluation of high school reform in Chicago. Although many efforts to improve Chicago high schools are concurrently under way, the focus of this evaluation is on three primary initiatives: Instructional Development Systems, Renaissance 2010, and Autonomous Performance Management Schools. The evaluation was initially designed to follow the initiatives for 4 years, but the Foundation decided to redirect its resources and end the evaluation after the first round of data collection. As a result, we report only on the implementation and early outcomes of the initiatives through fall 2008. Our reporting includes five documents, intended for multiple audiences. This overview summarizes the findings from each of the initiative reports and presents our cross-initiative analysis. The three initiative reports detail the implementation accomplishments and challenges, and describes early outcome data. In addition, the package of reports includes a detailed analysis of the observation data collected in 78 classrooms across all three of the initiatives.