Can market-based discipline enforce ESG standards along global supply chains? Using granular customer–supplier relationship data and ESG incident records, we show that input specificity fundamentally constrains supply-chain adjustment following negative environmental and social news. When inputs are standardized, ESG incidents significantly increase relationship termination; when inputs are highly specialized, relationships persist—even among highly visible firms. This constraint is especially binding for foreign suppliers. We find that ESG-induced terminations increase operating costs by 4.4 percent, compress markups by 6.7 percent, and reduce revenue-based productivity by 3.6 percent. These effects are concentrated in highspecificity and cross-border relationships, revealing structural limits to decentralized ESG enforcement in global production networks.