"This paper aims to evaluate the effectiveness of private food governance in addressing the environmental challenges facing the global food system, today. Greenhouse gas emissions, decline of biodiversity, water pollution, pesticide use and the generation of waster are considered the new agrarian questions of this century. Crucially, the governance of such environmental strains is a rapidly emerging issue for private actors, who have become key players in global food governance. Yet, few studies have tried to understand the actual impact of private rulesetting, in general, and retail governance, in particular, in detail. Drawing on global governance literature and organisational theory, this paper evaluates the effectiveness of private food governance institutions for sustainability, in terms of their comprehensiveness, stringency, compliance and coverage. Next to this quite narrow understanding of effectiveness the paper also identifies the broader political and soci-economic influence of private food governance in terms of structural, cognitive and normative effects. The paper illustrates its arguments in two cases, namely GlobalGAP and the Marine Stewardship Council. As such, the paper advances our theoretical knowledge on private rule-setting institutions and contributes empirically to political science research by making available new data on a currently understudied case of private governance." [author's abstract]