The emergence of undergraduate students serving in peer leader or peer educator roles is relatively recent in the history of higher education. Peer leadership positions were first recorded in 1959 in the field of student services, specifically working with students entering college and living in residence halls. Beginning with the Hazen Report of 1968, higher education has amassed a body of research that demonstrates peers' influence on new students. This scholarship shows a number of positive effects of peer education on student success. These effects--including increased satisfaction, persistence and retention, social development, and academic performance--have helped support the acceptance and proliferation of peer education and leadership in a number of areas within higher education. In order to better understand peer leadership roles on campuses today, it is helpful to explore the evolution of these roles from their origins in student services, most notably in orientation and residence life. After establishing this historic foundation, this article explores the perennial roles and changing responsibilities of students in peer leader positions as well as the trends that have influenced the growth of peer leadership within orientation and residence life. The article addresses emerging issues and future directions for the peer leader-educator role within these functional areas.