This book is a copy of the government agency publication. For most of our nation's history, coeducation has been the rm in our public elementary and secondary schools. In recent years, however, interest in public single-sex education has increased substantially. The No Child Left Behind Act of 2001 authorized school districts to use local or invative program funds to offer single-sex schools and classrooms consistent with applicable laws. Subsequently, the U.S. Department of Education published amendments to the Title IX regulations in October 2006 that would provide school districts additional flexibility to implement single-sex programs. In anticipation of an increase in the number of public single-sex schools, the U.S. Department of Education contracted with RMC Research Corporation to conduct a descriptive study of existing single-sex public schools that would address the following evaluation questions: 1. What is currently kwn about the effects of single-sex schooling on student achievement and other outcomes? 2. What is kwn about the causes of those outcomes? 3. What are the characteristics of public single-sex schooling? What are the contextual, instructional, and behavioral practices unique to single-sex schools? 4. What perceived benefits or disadvantages are associated with single-sex schooling? 5. What studies, including research questions and methodology, would be most appropriate to advance the kwledge base in this field? To address these questions the study includes a systematic review of the literature available in 2004, a survey of public single-sex schools, and a preliminary exploratory observational study of a subsample of currently operating public single-sex schools. The observational study was designed to yield three types of descriptive information about single sex schools: the schools' demographic characteristics, the professional characteristics of the teachers and principals, and the teachers' and principals' perceptions of the school characteristics. Both the survey and the observations were confined to those single-sex schools that were operational as of fall 2003. Although the study describes characteristics that are somewhat more prevalent in single-sex schools, the results are t causal evidence that single-sex schools improve the quality of academic and behavioral interactions between teachers and students. Instead, these descriptive findings are a potential source of hypotheses for further investigations that utilize experimental or quasi-experimental designs. Key findings that emerged from the study include: The results of the systematic review are mixed, though the findings suggest some support for the premise that single-sex schooling can be helpful. Among the concurrent academic accomplishment outcomes, 53 percent were null (favored neither single-sex r coed schooling), 10 percent had mixed results across sex or grade levels, 35 percent favored single-sex schooling, and only 2 percent favored coed schooling. Among the concurrent socio-emotional outcomes, 39 percent were null, 6 percent were mixed, 45 percent favored single-sex schooling, and only 10 percent favored coed schooling.