The present study investigated junior college students' conceptions of and approaches to learning via online peer assessment (PA) using a phenomenographic approach. Participants were 163 college students. Students were asked to accomplish a given learning task via an online PA system. Of the participants, 62 were interviewed after the activity. The interviews revealed hierarchically related and qualitatively different categories of conceptions and approaches to learning via online PA. The main and achieved levels of conceptions of and approaches to learning were determined. The results showed that, within each level, conceptions emphasizing a fragmented and cohesive learning tended to be associated with approaches focusing on surface and deep learning, respectively. In addition, students with cohesive learning conceptions and deep learning approaches were likely to make greater progress in the early stages of online PA activity. The present study finally found that approaches to learning via online PA were less related to the learning outcomes than conceptions of learning. (Contains 7 tables.)