This study examines the agencies responsible for investigating when a member of the public is seriously injured, is killed or experiences other serious and potentially criminal actions at the hands of police officers in Canada. The article takes a comprehensive approach by examining all police oversight agencies that are responsible for responding to and investigating allegations of police criminality—eight organizations, across nine jurisdictions. The study integrates insights from public administration and police accountability literature and examines the structures and administration of the agencies. The study provides a critical assessment of the state of police oversight for serious incidents in Canada, it identifies agency outputs (including case substantiation), levels of independence, efforts at transparency, and considers the challenges in attempting to hold police accountable in Canada.