Recent federal legislation, including the 1994 Improving America’s Schools Act, has enabled broad expansion of Title I schoolwide programs to over 8,000 schools across the nation. These regulatory changes are intended to reduce the historically fragmented or categorical character of title I programs and improve the effectiveness of entire schools rather than targeting services to meet the needs of the most disadvantaged subpopulations. Despite the dramatic increase in the number of schoolwide programs, there is little comprehensive information about them and their effectiveness relative to traditional Title I programming. This article presents a synthesis of what is known about Title I schoolwide programs, focusing on three aspects: characteristics of schools and districts implementing schoolwide programs, programmatic and organizational characteristics of schoolwide program schools and districts, and evidence of the effectiveness of schoolwide program schools, particularly in terms of student performance. In addition to reviewing these evaluation findings, we present several cautions related to their interpretation. Finally, we suggest implications for future evaluations and discuss policy implications for school improvement.