Differences in literacy growth over the summer versus the school year were examined to isolate how schooling affects children's literacy development from preschool through second grade across four literacy skills. Children (n = 383) were tested individually twice each year for up to 4 years on measures of phonological awareness, decoding, reading comprehension, and vocabulary. Growth curve analyses indicated that schooling effects were greatest for decoding skills and reading comprehension, were medium in size for phonological awareness, and were less evident for vocabulary. Except for vocabulary, relatively small amounts of growth were observed for preschoolers, followed by a period of rapid growth for kindergarteners and first graders, which slowed again for second graders. Findings demonstrate the differential effect of schooling on four separate literacy skills during the crucial school transition period. (Contains 2 figures and 6 tables.)