The present study is based on interviews of students (n = 48) and instructors (n = 27) from various disciplines in a North American research university and explores participants' comments on examples of some students' unacknowledged texts appropriated and drawn from published sources, classroom learning, or unidentified prior reading. Although many participants agreed that sources for some of these appropriated texts should be cited, they were split in their views about others. Chi-square values on the frequencies of these citation choices suggested complexity and high variability within groups of participants. In explaining their judgments, participants expressed various grounds for citation in relation to the notion of common knowledge, the audience effect, and the role of memory. The study suggests that motivations and considerations that might lead to citing or not citing are not apparent or subject to a consensus among people who share the same expertise, status, or language and cultural background. (Contains 4 tables and 1 figure.)