This article reports a case study that examined English as a Second Language students' peer response stances from an activity theory perspective. More specifically, the study was guided by the constructs of activity and motive/object in Leont'ev's theory. Multiple sources of data were collected from two native Spanish-speaking students enrolled in a low-advanced EAP writing class, including recordings of their peer response sessions and individual interviews. An inductive and recursive qualitative analysis approach was adopted to analyze the data. Transcripts of student participation in peer response sessions were analyzed to identify the two participants' stances during peer response, and interviews were analyzed to understand the students' motives/objects for participation in peer response. Data analyses indicate that each participant had a distinct motive/object for participating in peer response, and that these motives/objects motivated the students' peer response stances. Implications of the study for instructional practices and research are discussed.