Unlicensed boarding houses provide low cost accommodation for many people who have mental health and/or alcohol or other drug problems. The present study explored the needs and experiences of owners and managers of unlicensed boarding houses who have residents with MH and AOD problems. Twenty-three boarding house managers (BHMs) from Illawarra and Sydney areas participated in semi-structured interviews which were recorded and transcribed. Content analysis revealed most BHMs had very limited understanding of different types of mental health and substance use disorders. Almost all reported problems with individuals who they believed had such problems. Several BHMs found themselves in the role of "accidental counsellors", but their responsiveness to residents needs was highly variable. BHMs' inconsistent reactions to rule violations may create high levels of uncertainty amongst residents. The discussion describes options for addressing residents' needs including educational strategies for BHMs and facilitating links with support agencies.