This study focuses on two civil society coalitions advocating for sustainability transitions in the European Union (EU): the EU Food Policy Coalition and the less formally-organized coalition around the Blue Manifesto, both of which are understood in this article as intermediaries who connect local and national actors, activities, and ideas to the EU policy process. Using data collected through semi-structured interviews and drawing on frameworks developed by the literature on sustainability transitions, we provide a theoretically-informed discussion of these coalitions, analyzing their orientations, goals, and uniting frames. We find that these coalitions use a just transition frame that combines social as well as environmental dimensions and integrates the agendas of civil society groups within each coalition that focus on environmental goals with those of other groups that focus on broader social justice goals. Relatedly, these coalitions call for greater policy integration across social and environmental policy areas. Additionally, we find that sustainability transitions in the EU context are understood by the coalitions to entail not only significant shifts in policy, but also a commitment to a process that is more democratic and participatory. Finally, we find that in the context of multi-level governance, coalitions advocating for sustainability transitions involve Brussels-based organizations that focus on policy advocacy as well as national-level organizations that engage the general public. This article contributes to the literature two case studies that extend the theoretical formulations developed to study sustainability transitions to the transnational context, which has not been sufficiently explored in the sustainability transitions literature.