Education Matters' working hypothesis in this report was that the quality of implementation of ILT (Instructional Leadership Teams) and LASW (Looking At Student Work) groups is related to the quality of implementation of other components of reform. Specifically, the authors anticipated that schools in which ILTs and LASW groups were well-established would show considerable evidence of a collegial collaborative culture--including teacher leadership--that focused on instruction. And, they proposed that such schools would be better positioned to implement additional components of reform, for example, performance assessments. The data analysis by the authors supports this hypothesis. Schools with high-functioning ILTs and LASW groups had better established collegial, collaborative, instructionally-focused cultures than did schools with lower-functioning ILTs and LASW groups. These schools demonstrated greater in-school capacity to take on the work of implementing performance assessments than schools with low-functioning ILTs and LASW groups. As a result of this analysis, in light of the theory of reform that guides Boston's school improvements work, these schools are now well-positioned to continue improving teaching and thereby, student learning and measured achievement. Appended are: (1) Boston Public Schools Plan for Whole-School Change; Boston Plan for Excellence Expectations for Performance-Based Assessment; (3) Boston Public Schools Assessment System Based on Learning Standards and High Expectations; (4) Self-Assessment Summary; (5) Phases Chart, 1998; and (6) Up-Date and Phases Chart, 2000. (Author/MA)