In June 2016, the Mastery Collaborative completed its first year as an official program, working with more than 40 public middle and high schools across the five boroughs of New York City to improve, document, and advocate for mastery-based teaching and learning. The collaborative has eight Living Lab schools that practice schoolwide mastery; most Mastery Collaborative schools are Active Members, who may be earlier on in the progression toward schoolwide mastery. In this article, teachers and students share their experiences with mastery learning, and the Collaborative offers several insights to schools interested in implementing the approach.