The Roundtable on Sustainable Palm Oil, as a form of neoliberal environmental governance operating beyond-the-state, seeks to address its democratic deficit and gain legitimacy through deliberative and consultative processes. The Roundtable on Sustainable Palm Oil requires companies to conduct participatory social impact assessment for both new developments and existing operations in an attempt to identify and address the critical social impacts associated with palm oil production. Using a political ecology framework, and a mixed methods approach, this study explores social impact assessments as sites of power struggles, to understand the contestations, inequities, and marginalizations that occur in social impact assessment processes. By exploring the nature of social impact assessment as a market-led regime that privileges certain knowledges and politics, and is co-opted and controlled by powerful actors, the paper challenges the notion that social impact assessment can ensure the inclusion of previously marginalized people in decision-making processes. Participation in social impact assessment is found to be, at most, consultative and top-down, and risks the further disempowerment of affected peoples. By viewing social impact assessment as a discrete intervention, without a clear wider political project for social change for local peoples and workers, the Roundtable on Sustainable Palm Oil risks ‘rendering technical’ and ‘marketable’ the multifaceted social impacts associated with palm oil production as it simultaneously enacts particular global, neoliberal ‘participatory’ strategies that are applied locally in ways that (re-)produce hegemony and legitimacy.