Public investment in early childhood education has expanded dramatically in recent years. Despite this investment, we have little empirical evidence on whether children today know more at school entry than they did two decades ago. Using two large, nationally representative datasets, this paper documents how students entering kindergarten in 2010 compare to those who entered in 1998 in terms of their teacher-reported proficiency in reading and math and their behavioral skills. Our results indicate that students in the more recent cohort entered kindergarten more proficient at both reading and math skills. Improvements over this period were particularly pronounced among black and Hispanic students as well as low-income children. (author abstract)