The purpose of this study was to evaluate the efficacy of Promoting Acceleration of Comprehension and Content Through Text intervention implemented with 11th-grade students enrolled in U.S. History classes. Using a within-teacher randomized design, the study was conducted in 41 classes (23 treatment classes) with 14 teachers providing the treatment. Students in the treatment condition performed significantly better than students in the typical instruction comparison condition on a measure of content acquisition at posttest (ES = 0.36), as well as 4 (ES = 0.22) and 12 (ES = 0.24) weeks following treatment. There were no differences between treatment and comparison groups on measures of social studies reading comprehension or more general reading comprehension.