The role of peers in U.S. doctoral education is a topic that has been minimally researched and has received only passing attention. Yet peers are an important part of every doctoral learning community. One possible explanation for the lack of attention given to peers in doctoral education is that pedagogically, doctoral education is generally thought of as an apprenticeship in which doctoral students learn primarily from one master: their advisor. In this article, the authors argue that peers at the doctoral level are best understood as "learning partners." In support of this assertion, they present empirical evidence from two different studies that show the role that peers can play in the development of doctoral students into independent researchers and members of their academic community. The first study looks at the role of the apprenticeship model in doctoral education, and the second study is an evaluation of interdisciplinary doctoral initiatives funded by the National Science Foundation Integrated Graduate Education and Research Traineeship (IGERT) programs. Finally, the authors conclude that additional research is needed to further understand the unique dynamics of peer learning in doctoral education.