Scientific research has established that if all children are to achieve their developmental potential, it is important to lay the foundation during the earliest years for lifelong health, learning, and positive behavior. A central question is how well our public pre-kindergarten (pre-K) programs are doing to build this foundation. [...]. In “Puzzling it out: The current state of scientific knowledge on pre-kindergarten effects”, a task force comprised of social scientists from Brookings and Duke University lists six consensus statements on what we know about the effects of pre-K and highlights the importance of gathering further evidence to answer three important questions: What features of pre-K programs, specifically, put children on a positive developmental trajectory? What’s the best way to scale up small pre-K programs to a school-district or state-wide level? How can we use evaluations of an earlier generation of programs to guide the development of today’s pre-K programs? The consensus statement is part of this broader report.