As pre-K programming increasingly garners more political attention and funding in the states, policymakers are seeking the most up-to-date and rigorous research to support decision-making and creation or expansion of these programs. High-quality pre-K has bipartisan support in part because of the vast amount of existing research detailing positive benefits -- notably that it is of great benefit to students from low-income families and those who are dual-language learners. However, some research also demonstrates that positive growth among pre-K students isn't consistently sustained over time. This idea is known as "convergence" or "fadeout," because the short-term gains of pre-K attendees may diminish in early elementary school. The reasons for these mixed findings vary. Some researchers have pointed out that large-scale, public pre-K often varies in quality from program to program, making comparisons difficult. Others have suggested that the convergence effect may be a function of the instruction provided in kindergarten and early elementary grades, which often focuses heavily on improving the skills of struggling students who may lack access to pre-K rather than building on the skills of pre-K attendees. This Policy Brief analyzes 15 research studies on the effectiveness of pre-K outcomes in programs across the country and finds evidence of sustaining effects beyond kindergarten.