Sexual assault crisis hotlines provide crucial support for survivors. Though some hotline users engage in inappropriate conduct (e.g. prank or obscene calls), few studies explore these interactions. To address the lack of literature exploring inappropriate hotline interactions, we conducted a secondary data analysis of chat transcripts ( n = 233) shared with the research team as part of the formative evaluation of a university-based sexual assault program's web-based crisis hotline. From those transcripts, we analyzed potentially inappropriate interactions ( n = 38), most of which ( n = 28) hotline responders flagged as inappropriate in post-chat log forms. We used codebook thematic analysis to explore how hotline responders identified and navigated these interactions. Our analysis generated three themes describing the processes through which responders seemed to identify potentially inappropriate chats - detecting implausibly graphic and abusive content, identifying patterns of presumably inauthentic chat topics, and interpreting ambiguous content. Hotline responders seemed to navigate ambiguous and less egregious boundary violations by gently redirecting conversations, and addressed clearer violations by setting firm, direct boundaries. Chatters responded to boundary setting by desisting and disconnecting or attempting to reengage responders. Findings highlight ambiguities and challenges web-based sexual assault hotline responders face and suggest a need for additional responder support, training, and debriefing options.