In this experimental study we examined the effects of integrating teacher-directed knowledge-building and student-regulated comprehension practices in 7th- to 10th-grade English language arts classes. We also investigated the effect of instructional quality and whether integrating practices differentially benefitted students with lower entry-level reading comprehension. The study was conducted in 6 schools, involving 17 teachers and 921 students. Teachers' English language arts classes were randomly assigned to intervention (n = 36) or typical practice comparison (n = 29) conditions, and all teachers taught in both conditions. Students in both conditions grew significantly from pretest to posttest on proximal measures of narrative (ES = 0.09) and expository comprehension (ES = 0.22), as well as a standardized distal comprehension measure (ES = 0.46); however, no statistically significant between-group differences were found. Although intervention fidelity did not significantly influence outcomes, observational data indicated that teachers increasingly incorporated comprehension practices in their typical instruction. Effect sizes indicated a differential influence of entry-level reading comprehension on proximal and distal comprehension with higher performing readers in the intervention condition benefiting more than their lower performing peers on expository comprehension.