This study tested the effect of cooperative concept mapping on knowledge achievement and transfer in peace education on 159 social studies students using a quasi-experimental research design. Four intact classes-two each in rural and urban areas-were randomly assigned to experimental and control conditions, and two instruments-Peace Education Achievement Test and Peace Education Transferability Test-were used for data collection. Findings showed that cooperative concept mapping unveiled students' misconceptions in peace education and their perceptions about violent behaviors, raised students' consciousness about asymmetric structures undermining peace, empowered them with ability to establish connections between intrinsic and extrinsic causes of conflict, and encouraged practical suggestions on how to resolve conflict and promote peace through enactment of peace virtues. Bivariate associations showed that students' achievement in one context correlated with their transfer of learning in another context, with stronger correlation exhibited among experimental students. We attributed the stronger correlation recorded among experimental students to the "concepts connection" and visual effect occasioned by concept maps and overt effort of experimental teachers to create cooperative, experiential, and learner-centered lessons. Also, our assumption that female students will do better than male students in peace education was met. Implications of findings for curriculum review, instructional delivery and teacher education were discussed.