This report discusses the outcomes of a project that investigated elementary schools and classrooms that had a reputation for effective implementation of curriculum differentiation practices to meet the individual needs of high ability students. Using a multisite case study method, researchers conducted observations in classrooms and interviewed teachers, administrators, and students at 10 school sites to describe both the specific ways that teachers make accommodations for individual students and the factors that influence these practices. Results found that the classroom teachers implemented curriculum modification procedures, employed flexible grouping practices, provided advanced level content, or provided opportunities for advanced level projects to accommodate students' differing academic needs. At some sites, the teachers collaborated with the other teachers at their grade level or with district curriculum specialists to provide more academic challenges to talented students. In some situations, the teachers and parents described the leadership of school principals or superintendents whom they believed were responsible for teachers' instructional practices. A synthesis of the findings and themes across the 10 sites are included in the final chapter of the monograph. (Each site description contains individual references.) (Author/CR)