North America continues to witness escalating rates of opioid overdose deaths. Scale-up of existing and innovative life-saving services - such as overdose prevention sites (OPS) as well as sanctioned and unsanctioned supervised consumption sites - is urgently needed. Is there a place for critical theory-informed studies of harm reduction during times of drug policy failures and overdose crisis? There are different approaches to consider from the critical literature, such as those that, for example, interrogate the basic principles of harm reduction or those that critique the lack of pleasure in the discourses surrounding drug use. Influenced by such work, we examine the development of OPS in Canada, with a focus on recent experiences from the province of Ontario, as an important example of the impacts associated with moving from grassroots harm reduction to institutionalised policy and practice. Services appear to be most innovative, dynamic, and inclusive when people with lived experience, allies, and service providers are directly responding to fast-changing drug use patterns and crises on the ground, before services become formally bureaucratised. We suggest a continuing need to both critically theorise harm reduction and to build strong community relationships in harm reduction work, in efforts to overcome political moves that impede collaboration with and inclusiveness of people who use drugs. Copyright © 2019 Elsevier B.V. All rights reserved.