Background: Research reveals that explicit reading strategies instruction and engaging students in interaction about texts promote students' reading comprehension ability. The present intervention study combines both aspects. Aims: The study examines the educational benefits of explicit reading strategies instruction, followed by practice in (a) teacher-led whole-class activities (STRAT), (b) reciprocal same-age (STRAT + SA), or (c) cross-age peer tutoring activities (STRAT + CA) on fifth graders' reading comprehension achievement. Sample: Twenty-two fifth-grade teachers and their 454 students from 19 different schools throughout Flanders (Belgium) participated. Method: A quasi-experimental pretest post-test retention test design was used with three experimental (STRAT, STRAT + SA, and STRAT + CA) and a matched control group. The experimental interventions were implemented during an entire school year. Results: Multilevel analysis revealed that the STRAT and STRAT + CA condition made a significantly larger pretest to retention test progress than the control group. The significant major progress was especially situated from pretest to post-test, during which the intervention took place. Concerning the STRAT + SA condition no significant differences with regard to the control group were detected. Pairwise comparisons of the experimental conditions indicated that the STRAT + CA condition's progress from pretest to retention test also exceeded the STRAT + SA condition's advancement significantly. Conclusion: The study corroborated the efficacy of the STRAT and STRAT + CA conditions' interventions as feasible tools to enhance fifth graders' reading comprehension achievement.