California's Kindergarten Readiness Act of 2010 revised the cutoff date by which children must turn five for kindergarten entry in that year and established transitional kindergarten (TK), defined as the first year of a two-year kindergarten program for all students affected by the birthdate eligibility change. Since it has been implemented across…

Forty years ago, 96% of six-year-old children were enrolled in first grade or above. As of 2005, the figure was just 84%. The school attendance rate of six-year-olds has not decreased; rather, they are increasingly likely to be enrolled in kindergarten rather than first grade. This paper documents this historical shift. We show that only about a…