Relatively few rigorous studies of the effectiveness of contemporary public prekindergarten programs have been conducted despite the growing number of programs and large monetary investments that accompany them. The study on which this presentation is based was launched in partnership with the Tennessee State Department of Education's Division of School Readiness and Early Learning to provide an assessment of the effects of the statewide Tennessee Voluntary Pre-Kindergarten (TN-VPK) program on the readiness for kindergarten of the economically disadvantaged population it serves. TN-VPK has become a controversial program in Tennessee, with some legislators expressing doubts about its value in the context of severe budget shortfalls and still others referring to it even more skeptically as expensive babysitting. This study interleaves a randomized control trial (RCT) design and an age-cutoff regression discontinuity (RD) design to evaluate the effectiveness of the TN-VPK program. Though the project is still underway, this presentation will summarize results from the RCT through first grade. One table is appended.