This study investigates faculty perceptions of teaching information literacy. Using 24 semi-structured interviews, a phenomenographic approach identified four qualitative ways in which faculty experienced teaching information literacy (IL). This paper analyzes the challenging information literacy concepts that faculty identify--known to many librarians as "threshold concepts"--and their relationship to the Association of College and Research Libraries (ACRL) "Framework for Information Literacy for Higher Education." The study highlights the transdisciplinary nature of IL instruction and indicates that, although unaware of the ACRL Framework, faculty already teach at least three concepts from that document. This finding suggests new opportunities for collaborations between librarians and faculty.