Research on regulation and regulatory processes has traditionally focused on two prominent roles: rulemaking and rule-taking. Recently, the mediating role of third party actors, regulatory intermediaries, has started to be explored–notably in a dedicated special issue of the ANNALS of the American Academy of Political and Social Science. The present special issue extends this line of research by elaborating the distinction between formal and informal modes of regulatory intermediation, in the specific context of transnational multistakeholder regulation. In this introduction, we identify two key dimensions of intermediation (in)formalism: officialization and formalization. This allows us to develop a typology of intermediation in multistakeholder regulatory processes: formal, interpretive, alternative, and emergent. Leveraging examples from the papers in this special issue, we discuss how these four types of intermediation coexist and evolve over time. Finally, we elaborate on the implications of our typology for regulatory processes and outcomes.