As outer space becomes more congested, contested, and competitive, the risks to space safety, security, and sustainability heighten. Against this backdrop, the authors used a review of relevant literature and official documents, as well as interviews and workshops with subject-matter experts, to identify possible lessons for future space traffic management (STM) from past approaches to international traffic management and common resource management and offer recommendations to make progress in STM. Lessons from the history of the maritime and air domains and the development and implementation of international organizations within those domains help provide a pathway for the development of an international space traffic management organization (ISTMO). An ISTMO will need to achieve sufficient legitimacy and operational power to effectively manage the space domain.