Contribution: This article describes how a peer learning strategy called student-led tutorials (SLTs) can improve student performance in an electromagnetism course (EM). This study provides empirical evidence on how promoting student active participation in collaborative problem-solving activities improves performance rates. Background: In 2019, an EM bachelor course introduced SLTs as a strategy to improve the 40% passing rates. Before SLTs, students perceived this course as very hard, uninteresting, disengaging, and nonfundamental to their studies. Intended Outcomes: A participatory environment that promotes active learning can deepen understanding of EM through problem discussion and peer collaboration. Application Design: This study uses an action research approach to analyze teaching practices and students performance. Based on this analysis, SLT is implemented and the results are examined. Drawing on professors' research on engineering education, traditional practice hours were transformed into SLT hours. Passing rates before and after the intervention were compared and correlated with SLT participation. In-depth qualitative interviews with students were conducted to understand how SLT related to their learning process. Findings: Since the intervention, the course passing rates increased 20%. More importantly, the grade distribution changed from a steep double exponential shape to a normal curve suggesting more students are doing better. There is a positive correlation between SLT participation and student performance. Students highly valued SLTs as a teaching strategy because it allowed discussion, enabled keeping up with the course pace, and created a culture of collaboration. Students also valued the mandatory aspect of SLTs, though they mentioned it increased the course workload.