RT Journal Article SR Electronic T1 Expanding Exposure JF Journal of Human Resources JO J Hum Resour FD University of Wisconsin Press SP 373 OP 402 DO 10.3368/jhr.46.2.373 VO 46 IS 2 A1 Frisvold, David E. A1 Lumeng, Julie C. YR 2011 UL http://jhr.uwpress.org/content/46/2/373.abstract AB Coinciding with the work requirements of welfare reform in the mid-1990s, the early childhood education program, Head Start, significantly expanded to increase the availability of full-day classes. Using unique administrative data, we examine the effect of full-day compared to half-day attendance on childhood obesity. This effect is identified from changes in obesity over time and from the elimination of a state-provided full-day expansion grant that decreased the supply of full-day classes. Our results suggest that full-day Head Start attendance significantly reduces the proportion of obese children at the end of the academic year.