There is no more pressing problem in education today, writes the author, than closing the achievement gap between low-income urban schools and more advantaged predominantly suburban schools. A study by the Center for Education Research & Policy at MassINC (CERP), identifies some of the characteristics of higher-performing urban high schools in Massachusetts. On the most general level, the CERP findings are consistent with a significant academic literature on effective urban high schools. Such schools are typically marked by a culture that is highly focused on a core academic curriculum and college preparation. The faculty are highly skilled and share a commitment to work together to foster the success of all students. Students are known by their teachers and receive personalized support and encouragement. There are clear, agreed-upon standards of performance for all members of the school community with bonds of mutual commitment and obligation to achieve the school's mission. Examination of the schools included in the CERP study suggests certain principles that, if applied to urban high school reform, may lead to greater success for urban youth: (1) Small is better; (2) Autonomy on matters of staffing, budget, curriculum, governance, and time is as critical as size; (3) Choice is associated with achievement; (4) Extra resources make a difference; (5) Well-conceived, structured, and supported inclusion programs can be effective in educating English language learners and students with special needs; (6) College and community partnerships help; (7) Incorporating earlier grades is a potent strategy for closing the achievement gap in high school; and (8) Stronger school and student accountability provisions make a difference in creating academically challenging communities of learning. Recommendations are included for both state and district level. Appendix contains: Characteristics of Selected High-Performing Schools. (Contains 8 endnotes.)