Transnational private governance schemes, like other global rule-making arenas, are confronted with the challenges of North-South imbalances. Through their standards and certification processes, private governance schemes aim to control access to the market for sustainably certified products and may consequently generate or perpetuate global inequalities. Are these imbalances inevitable and likely to persist? This article explores North-South imbalances in the operations of the Marine Stewardship Council (MSC), a leading standard-setting and certification scheme for capture fisheries. We examine whether the scheme’s Northern-dominated origins reflect pre-existing structural imbalances, persist through path-dependent processes, or can be addressed by scheme adaptations. Our analysis uses data on the 312 fisheries that have engaged with the MSC from 1999 to 2015. We find evidence that imbalances in the MSC reflect corporate power and structures of power in the global fisheries sector, but that path dependence has also elevated the power of unexpected countries. Adaptations to date have been less successful as a means to lessen Northern dominance.