Boston's public charter school sector has received national attention for its strong student outcomes. Independent studies have found that Boston charter school students, on the whole, are learning at much faster rates than their peers in charter schools across the country, as well as in local district schools -- even while Boston Public Schools remains one of the highest performing urban districts in the country. What's happening in Boston's charter schools to make them so effective? Part of the answer may lie in a set of specific school leadership practices that cultivate environments that promote quality instruction. The environments where they work, and particularly the school leaders who nurture and shape those environments, play an important role in setting teachers up to do their best work in the classroom. We've been investigating the importance of school environment and leadership practices for several years, using a survey tool called Instructional Culture Insight, which measures teachers' perceptions of their school environments. In "Greenhouse Schools: How Schools Can Build Cultures Where Teachers and Students Thrive (2012)", we found that school culture matters for the retention of high-performing teachers and for student achievement overall, and we identified a handful of elements that seem to be consistent across schools with particularly positive environments -- places we refer to as "greenhouse schools."