Play researchers and theorists have cautioned that children's early play is changing in a manner that is detrimental to their development. Meanwhile U.S. governmental pressures and increasingly higher standards for education are changing the landscape of kindergarten and early learning. This study investigates the relationship between children's out-of-school play and their educational readiness. Parents of kindergarten students in a suburban Midwestern school district completed the "Child Play Survey" on time their children spent in out-of-school play. Kindergarten teachers rated students on three domains of readiness using the newly devised Illinois Kindergarten Individual Development Survey (KIDS 2015): "Attention to Learning-Self-Regulation" (ATL-REG); "Social and Emotional Development" (SED); and "Language and Literacy Development" (LLD). Correlational and regression analyses suggest that time in out-of-school play is not positively associated to teacher ratings of academic and behavioral performance in kindergarten. Rather, increased time in outdoor play on school days and non-school days resulted in lower scores on all three readiness domains. Time in outdoor play was correlated to free-reduced lunch eligibility, the socioeconomic measure utilized in the study. Parent education level, income level, attendance at 3-year-old preschool and daycare attendance were found to positively influence readiness measures. Implications for future research are presented.