This executive summary presents highlights from a study exploring the concept of teacher ownership and how it can bring about the deep and meaningful changes that schools need and that all students deserve. Based on teacher surveys and interviews in twenty-one schools in Los Angeles that are implementing major reforms, the study suggests that teacher ownership -- a teacher's sense of alignment with an improvement effort and agency to influence it -- exists where teachers are able to co-construct knowledge and to influence and lead school improvement efforts. Further, teacher ownership develops when supports and practices are in place that allow teachers to break down barriers and work collectively to build system coherence. Teacher ownership is not built in isolated classrooms. Rather, it is nested within a school culture that recognizes and values teachers' deep understanding that schools are social and cultural institutions and that values teachers' expertise and knowledge. This study builds on previous research by aiming to measure the degree of ownership that teachers have gained in a network of schools within the Los Angeles Unified School District (LAUSD) that is working to transform and ameliorate educational inequalities by broadening students' learning opportunities. Findings are based on a mixed-methods study that included the administration of teacher and administrator surveys across twenty one schools implementing three approaches as well ad interviews and observations at three case study sites. Recommendations are presented. [For the full report, see ED574745.]