The Center for the Future of Teaching and Learning (CFTL) at WestEd led the Teacher Practice Networks (TPN) initiative for five years, with support from the Bill & Melinda Gates Foundation. Initial rounds of Gates funding supported 21 education improvement organizations in disseminating standards-based resources around the nation. Later rounds of funding supported 14 organizations to sustain the dissemination work, and additionally to concentrate on developing teacher leadership as a means to bring the standards to life in classrooms. The TPN was formed on the premise that teachers learn best from one another and that teacher leadership within schools can positively impact instruction. The results of the TPN initiative lend grounding to that premise. The 14 grantee organizations supported the development of more than 1,000 teacher leaders who helped 10,000 of their colleagues use standards-aligned practices in their classrooms. Inverness Research evaluated the initiative and studied its design. Two lenses on the TPN reveal how and why the initiative was effective in advancing awareness and implementation of the new standards. One lens is on its anatomy. This paper dissects the structures of the TPN, from the architecture of the overall initiative to the micro-designs for professional learning within schools, to examine the functions of each. The layers of structure worked together to achieve the goal: to transform Common Core standards from their origin in policy (and politics) to their expression in classroom practice. We also examine the TPN as a learning initiative. Elements of culture and leadership animated the structural elements in ways that promoted reflection, learning, and improvement at the teacher, organization, and network levels. The structural and cultural elements of the TPN functioned well as an infrastructure for educational improvement. The case of the TPN highlights the need for steady investment in such infrastructures. [This report was written with assistance from Allison Murray.]