This study examines the impact of the Learning Strategies Curriculum (LSC), an adolescent reading intervention program, on 6th- and 9th-grade students' reading comprehension and strategy use. Using a randomized treatment-control group design, the study compared student outcomes for these constructs for 365 students who received daily instruction in 6 LSC strategies and 290 students who did not receive intervention instruction. After 1 school year, 6th-grade students who received intervention instruction significantly outperformed students in the control group on a standardized measure of reading comprehension and reported using problem-solving strategies in reading to a greater extent than students in the control group. There were no significant differences between 9th grade intervention and control groups in reading comprehension or strategy use. (Contains 16 tables.)