Environmental non-governmental organisations stood out during the 2016 European Union referendum campaign. Despite clear reputational and regulatory risks, they participated in this fraught political debate in sharp contrast to other civil society sectors. This challenges common assumptions that material concerns, and ultimately survival, prevail in campaigning choices. We argue that campaigning choices reflect commitments to values that underpin these organisations' raison d'etre. Drawing on a pragmatist view of organisations, we analyse how external (media, regulatory) and internal (competence, governance processes) pressures shaped the campaigning choices of nine UK environmental organisations. We find that most environmental non-governmental organisations chose to engage, some even officially registering for Remain. Those active at the European Union level were most likely to engage - but also most open to criticism. Overall, environmental non-governmental organisations struggled to adapt their usual expertise-based, elite-focused campaigning style to the referendum which raises questions for civil society's ability to speak for Europe, and contribute to controversial democratic debates, beyond the United Kingdom.