This study examined the efficacy of a shared book-reading approach to integrating literacy and science instruction. The purpose was to determine whether teaching science vocabulary using information text could improve low-income preschoolers' word knowledge, conceptual development, and content knowledge in the life sciences. Teachers in 17 preschool classrooms and 268 children participated; nine classrooms were assigned to treatment, eight to control. The treatment group received a science-focused shared book-reading intervention, 4 days a week, 12-15 minutes daily for 12 weeks, while the control group continued with business as usual. Results indicated statistically and practically significant effects on children's word, concepts, and content knowledge and knowledge of the information text genre compared to the control group. However, we recognize the potential confound of district with treatment condition as a major limitation of the study.