New American Schools (NAS) offers whole-school designs for schools and districts seeking to significantly raise the achievement of large numbers of students; RAND evaluated NAS reforms1 effects on students and teachers in high-poverty schools. A decade ago, New American Schools (NAS) launched an ambitious effort for whole-school reform to address the perceived lagging achievement of American students and the lackluster school reform attempts that have produced so few meaningful changes. As a private nonprofit organization, NAS set out to help schools and districts significantly raise the achievement of large numbers of students by offering whole-school designs and design-based assistance during the implementation process. NAS is currently in the scale-up phase of its effort, and its designs are being widely diffused to schools across the nation. During the 1997-1998 and 1998-1999 school years, RAND assessed the effects of NAS designs on classroom practice and student achievement in a sample of schools in a high-poverty district. RAND found that high-poverty schools often have fragmented and conflicting environments with difficult and changing political currents and entrenched unions. Teachers in high-poverty schools tend to face new accountability systems and fluctuating reform agendas. These teachers generally lack sufficient time for implementing reform efforts, often becoming demoralized and losing their enthusiasm for the difficult task of improving student performance under difficult conditions. RAND concluded that high-stakes tests may motivate schools to increase performance and to seek out new curricula and instructional strategies associated with comprehensive school reforms. However, those same tests may provide disincentives to adopt richer, more in-depth curricula that can succeed in improving the learning opportunities of all students, particularly those in high-poverty settings. (cp)