Background Against the backdrop of the U.S. opioid epidemic, there has been a concerted movement to improve access to buprenorphine maintenance therapy (BMT). In Pennsylvania, where overdose mortality increased 65% between 2015 and 2017, over $75 million has been appropriated toward BMT since 2016. Concurrently, efforts to increase BMT availability while lowering barriers to entry have given way to fears of increased diversion and illegitimate patients. Little is known about the circumstances and motivations that surround buprenorphine diversion, particularly within the context of treatment expansion. Method Drawing on 27 in-depth interviews with individuals who reported sharing or selling buprenorphine in the past year, in this study we consider the relationship between treatment access, treatment experiences, and individuals’ decision to divert buprenorphine, while further comparing motivations for buprenorphine diversion across two Pennsylvania counties with disparate levels of BMT availability. Results We identify four styles of buprenorphine diversion (“ad hoc sellers,” “concerned suppliers,” “social sharers,” “professional dealers”), with different levels of representation by county. Overall, our analysis found the explicit economic exploitation of BMT was rare, while a plurality of participants reported selling unwanted or unneeded buprenorphine only when presented with an opportunity. Conclusions Across our typology, market demand in the form of unmet need for buprenorphine was the major driver of diversion, suggesting that “supply-side interventions” intended to again limit access to BMT may be counterproductive.