This article evaluates the utility of the Early Authors Program, a 12-month early literacy intervention emphasizing highly meaningful language interactions that was implemented in childcare facilities in an ethnically and linguistically diverse, urban, low-income community. Children learn to be writers and readers by creating their own self-authored, storybook texts, supported by the sensitive guidance of adults. Children (n = 280) in 32 experimental group centers and children (n = 87) in 9 similar control group centers were individually assessed at pretest and posttest on measures of language and cognition. Teachers completed pretest and posttest surveys and interviews, and interventionists were also interviewed. 3- to 5-year-old children receiving the intervention, as predicted, made significantly greater gains than the control group specifically on the child language measures but not on other measures. The quality of the classroom literacy environment and teachers' literacy-promoting practices improved considerably in centers receiving the intervention. Teachers reported high satisfaction and sustainability for the program. (Contains 5 tables and 2 figures.)