Marc Mauer delivers the 2015 Lillie and Nathan Ackerman Lecture. This lecture examines how and why the climate for criminal justice reform has changed over the past decade. Is the new political environment being driven by fiscal interests, changes in drug war politics, concerns over racial/ethnic disparities, or compassion for those who are incarcerated? Mauer assesses how far the reform movement has come and what changes in policy and practice are necessary if we seek to end mass incarceration in the United States. Opening remarks are provided by Prof. David Birdsell, Marianne Engelman Lado, and Prof. Byron Price.