In 1988, only one-half of Philadelphia 9th-graders in comprehensive high schools moved into 10th grade. In the same year, The Pew Charitable Trusts funded the Philadelphia Schools Collaborative (PSC) to seed the restructuring of the city's 22 comprehensive high schools. With a set of programmatic guidelines culled from successful efforts across the country, the Collaborative, in partnership with the school district, initially focused on ninth-graders, the students most vulnerable to failure, and then broadened to include the restructuring of entire schools. How the reforms fared at five high schools is the subject of this report. Data were collected through observation; personal interviews with 111 teachers, 38 students, and 17 administrators; and focus-group discussions with 32 teachers and with 294 students. The report presents case studies of the five high schools, and describes the basic ingredients for school learning communities, for professional development, and for critical reflection. The biggest restructuring dilemma was the segregation of students into tracked programs, which reinforced the attitude that only some students could achieve and that implicitly validated race and class assumptions. Appendices contain information about the Philadelphia Schools Collaborative and suggested research activities. (Contains 21 references). (LMI)