["Corporate Social Responsibility and Environmental Management, Volume 33, Issue 2, Page 2802-2816, March 2026. ", "\nABSTRACT\nSustainability barriers are often analyzed in isolation, yet their interactions shape supply chain sustainability collaboration (SCSC) and triple bottom line (TBL) performance. Drawing on stakeholder and coordination theories, this study examines how internal and external barriers jointly impact SCSC and, in turn, economic, social, and environmental outcomes. Using structural equation modeling with data from medium and large US corporations, findings reveal that SCSC mediates the relationship between external barriers and performance. Moderated mediation results show that internal barriers, often seen as detrimental, can paradoxically enhance organizational responses to external barriers. This dual role suggests that strategically managing—rather than merely minimizing—internal barriers can enhance collaboration and TBL performance. Given global supply chain interdependencies, our findings offer critical insights for managers and policymakers, emphasizing strategies that leverage internal barriers while mitigating external ones to enhance sustainability in complex regulatory and market environments.\n"]