This paper investigates how the peer agent's learning competency affects English learners' reading, engagement, system self-efficacy, and attitudes toward the peer agent in a trialogue-based intelligent tutoring system (ITS). Participants learned a summarizing reading strategy in the compare-contrast text structure in the ITS. Results detected the significant main effect of the peer agent's learning competency on learners' performance and on engagement. [This paper was published in: C. Conati, N. Heffernan, A. Mitrovic, and M. F. Verdejo (Eds.), "Proceedings of 17th International Conference on Artificial Intelligence in Education" (pp. 694-697). Cham: Springer.]