The Better Math Teaching Network offers a promising, practical model for teacher learning. Its practitioner members--who all teach at least one section of high school algebra and all joined voluntarily--are working with each other and a team of researchers to make their teaching more student-centered through an improvement science approach. With frequent in-person and virtual meetings, network members come together to share what they discover as they test and refine new instructional routines in their classrooms. This networked improvement community hypothesizes that student-centered learning could solve the problem of student disengagement in Algebra 1, a course with outsized influence on students' academic and career trajectories. Anticipating powerful lessons, Nellie Mae invested in a multi-year developmental evaluation to provide timely and actionable information to network leaders and members, while also informing the education field. Now in its second year, the network is evolving steadily and the learning has been rich. As educators discover practices that make a difference for their students, Nellie Mae is also learning about the structures and conditions that support effective teacher networks and that foster instructional improvement at scale. This report offers highlights from Year 2 of the Better Math Teaching Network. [For "Better Math Teaching Network: Lessons Learned from Year 2," see ED608796. For "Better Math Teaching Network: Year 2 Developmental Report," see ED608795.]