Effectively addressing concerns about assistance animals in any library setting is often problematic due to a lack of awareness about assistance animals in general, which then leads to uncertainty on how to proceed in these situations. Library personnel, regardless of library type, are often unaware of legal definitions of assistance animals. When compelled to respond to a patron complaint about “a dog in the library,” many library professionals are uncertain about which questions they may legally ask a patron who is accompanied by an animal. This uncertainty then creates concern about how to act in these situations, and thus, many library personnel may seek to avoid it entirely. However, with knowledge, time, some organizational development, and the appropriate legal vetting, it is possible to establish a best-practices protocol for handling complaints or concerns about patrons with an assistance animal in a library. This article details one such case study at an academic library in the Pacific Northwest.