The proposed paper and presentation will detail the results of a full-day kindergarten (FDK)impact study in a Midwestern state. The evaluation explores the impact of FDK as compared to half-day kindergarten (HDK) by utilizing data from natural experiments occurring in districts across the state. The state in question passed legislation which provided funding to increase access and availability of FDK in the 2007-08 school year, with grants targeted directly to school districts and charter schools. The legislation also charged the state department of education and board of education with evaluating the impact of FDK. This paper explores specifically FDK impact on participating students' literacy outcomes. The abstract outlines the study approach and design intended to address the fundamental question of whether FDK affects participants' reading readiness. (Contains 7 tables.)