Sustainability transitions encompass changes in existing socio-technological systems. In this context, scholars have emphasized the roles that intermediaries can play for sustainability transition. However, in the literature, the organizations or actors considered to act as intermediaries are very diverse and the concept of intermediary is used interchangeably between contexts. There is a risk that policy makers face difficulties understanding differences among intermediaries and consequently use some intermediaries for unfitting purposes. In this article,we propose to identify the similarities and differences among intermediaries, which are relevant for policy design for sustainability transitions. We base our comparison on three main characteristics:intermediaries’ source of funding, their scope of action and the target recipients oftheir services. Our analysis indicates that these differences have an impact on intermediaries’ short-term or long-term orientation, actor-level or system-level focus, and demand-side or supply-side target. We end the article by discussing the implications for policy design.