The Wisconsin Early Child Care Study (WECCS) is a validation study undertaken to better understand whether Wisconsin's YoungStar Child Care Quality Rating and Improvement System (QRIS) rating scale is functioning as intended. That is, the study is designed both to explore whether the rating scale is able to differentiate programs according to their levels of observed quality and whether children who attend more highly rated programs gain more in terms of school readiness over the course of a school year than children attending programs rated at lower levels. This report focuses only on the second validity question about whether YoungStar rating predicts differing levels of school readiness among children ages 3 to 5. (author abstract)