This study investigated the effectiveness of the peer tutoring instructional strategy in improving students’ academic achievement in financial accounting concepts. A nonrandomized pretest-posttest control group quasi-experimental design with a 2 × 2 × 3 factorial matrix was adopted. The research sample comprised 137 purposively selected students from eight intact classes in secondary schools in Southern Nigeria. The experimental group adopted a peer tutoring instructional strategy, while the control group was exposed to the conventional lecture method. Teachers’ Instructional Guides on peer tutoring and conventional method and Financial Accounting Achievement Test were used to collect data for this study. Results affirmed that the peer tutoring instructional strategy is more effective in improving students’ academic achievement in financial accounting concepts than the conventional lecture method. The outcome of this study also shows that the experimental strategy was not sensitive to gender but sensitive to socioeconomic status. Sequel to this finding, the study recommends that post-basic school teachers should make use of the peer tutoring instructional strategy to present financial accounting lessons in secondary schools to advance students’ attainment in the subject.