Over the past several years, many of the companies collectively known as Big Food have launched ambitious programs to assess and improve the sustainability of their raw material supply chains. Fueled partly by concerns about the risks posed by climate change and other environmental problems, these efforts differ from earlier corporate food supply chain governance in that they rely more on metrics of continuous improvement than compliance with standards. They also extend beyond high-value, high-profile products to include staple ingredients such as corn and soy. These commodities are sourced through long, complex, and traditionally nontransparent supply chains, where even the biggest food companies exercise surprisingly little clout over producers. This article examines how companies contend with this problem both within their own supply chains and as members of multistakeholder initiatives. The assemblage concept not only describes the many actors, technologies, and practices now working to get certain kinds of data flowing off farms; it also highlights the relational nature of this work and the uncertainty of its outcomes. More broadly, the article points to the limits of both corporate food power and the very notion of Big Food as an explanation for how that power is wielded.