In 2014 the Physics Department at Simon Fraser University (SFU) began a peer tutoring program to support the students enrolled in our two “Physics for the Life Sciences” first-year courses. Four undergraduate students who earned high grades in these courses were recruited to be volunteer peer tutors and run weekly drop-in tutoring sessions. We specifically chose students majoring in the life sciences and/or planning to attend medical school so that they would be true peers to the students in these courses. In 2016 this program was expanded to encompass three additional subject areas: Biology, Chemistry and Mathematics. In the same year with support from the SFU Institute for the Study of Teaching and Learning in the Disciplines, we conducted a study to determine the impact of this peer tutoring program on both the students being tutored (the tutees) and the tutors themselves. We administered surveys and conducted focus groups and interviews with both the tutors and the tutees in order to determine the influence their experiences with peer tutoring had in three arenas: enhanced learning, social experience and sense of agency. In addition we looked at the effect of peer tutoring on the academic performance of students who attended a significant number of tutoring sessions. The results of these investigations will be presented. We will also discuss how this program continues to grow at SFU beyond its humble beginnings and our plans for the future.