This summary provides an overview of a study that compared children's learning in full- and half-day kindergartens. Data from The Early Childhood Longitudinal Study -- Kindergarten cohort (ECLS-K), as well as background information collected from parents and administrators were used in the evaluation. Major findings include: an increase in math and literacy learning for full-day attenders; equal benefits for children of different social backgrounds attending full-day; and the discovery of several demographic trends.