We developed and evaluated an intervention that teaches reading comprehension via expository text structure training to second graders in urban public schools at risk for academic failure. Fifty lessons on 5 basic text structures (sequence, comparison, causation, description, and problem-solution) were embedded in a social studies curriculum that focused on U.S. historical communities. Second-grade classrooms were randomly assigned to 1 of 3 experimental conditions: the intervention, a comparison program that focused on the social studies content and did not include text structure training, and a no-instruction control. Sixteen classrooms (N = 258) completed the study. The performance of the intervention group was higher than that of the other 2 groups on reading comprehension measures based on written summaries, demonstrating the effectiveness of the intervention. On social studies content measures, the intervention and the content groups showed higher performance than the control group, indicating that embedding the text-structure training did not lessen the amount of social studies content acquired. The study confirms previous findings and extends our earlier work by showing that all 5 basic text structures can be taught to second graders effectively within the academic year. Robust transfer effects were found on typical reading comprehension tasks (sentence completion, questions) when the text continued to be well structured, and there was also evidence of transfer to authentic (ill-structured) text.