The long-run impacts of early childhood education

"We investigate short and long-term effects of early childhood education using variation created by a unique policy experiment in British Columbia, Canada. Our findings imply starting Kindergarten one year late substantially reduces the probability of repeating the third grade, and meaningfully increases in tenth grade math and reading scores. Effects are highest for low income students and males. Estimates suggest that entering kindergarten early may have a detrimental effect on future outcomes"--National Bureau of Economic Research web site.