In this article the authors analyse social partner engagement in European sectoral social dialogue, testing two prominent theories to disentangle sector and country dynamics: institutional and resources and capabilities theories. While institutional theory accounted for certain social partner preferences, resources and capability theory proved stronger in predicting participation and provided insight into regulatory preferences. The authors conclude that resources and capability theory better explains their case, associating it with weaknesses of transnational governance. Specifically, limited incentives for participation mean that social partners with fewer resources forego participation, entailing pre-eminence of social partners with greater resources and hindering outcomes reflecting national institutional influences.