Private standards are spreading rapidly in international food production and trade, and are moving beyond food quality and safety aspect to address environmental and ethical concerns. We examine how effective private standards are in improving employment conditions in global food supply chains. Using panel data from company and workers surveys and different econometric techniques, we analyze how the adoption of a variety of private standards, that differ with respect to their focus on labor standards, influences employment conditions in production, processing and exporting companies in the horticultural export chain in Peru. We find that workers employed in companies adopting private labor standards are more likely to be paid a minimum wage, to have a contract and to receive training but there is no effect of private standards on the level of the wage and on the employment period. We conclude that private labor standards contribute to the enforcement of national labor laws but have no beneficial effect beyond legal employment entitlements; and that despite the enactment of labor regulations at the national level and the wide spread of private labor standards, ethical labor concerns remain an issue in the Peruvian horticultural export sector.