What are the policies, programs and practices that make some high schools in the same state and district context more effective than others? Motivated to understand the differences between schools with similar size and demographics yet different attendance, graduation and levels of student academic growth, the National Center for Scaling Up Effective Schools (NCSU)--a federally-funded project aimed at identifying, developing and implementing processes to scale up effective practices in urban high schools--embarked on year-long initiative to identify the major differences between two high and two low performing high schools in two districts--Broward County, Florida and Fort Worth, Texas. The study and findings are discussed in this report. In both districts it was found that the more effective high schools successfully mobilized both the academic and social emotional systems at their schools in the service of students. Administrators, guidance counselors and teachers at the effective schools worked together to bridge the academic and social emotional elements of schooling, seeing them as interwoven. They implemented teaching strategies, cultural habits, and organizational routines that promoted interconnections between the classroom and the social emotional lives of students. As such, students in the higher performing schools were much more likely than those in the lower performing schools to say that adults in the school supported them in developing both cognitive and non-cognitive skills necessary for their academic success and social wellbeing. Further, the high performing schools in the districts mobilized these academic and social emotional practices in different ways, particular to their local context and needs.