["Corporate Social Responsibility and Environmental Management, Volume 33, Issue 4, Page 4883-4902, July 2026. ", "\nABSTRACT\nThis study investigates differences in environmental, social, and governance (ESG) performance between family and non‐family firms, using panel regression models with year, industry, and exchange fixed effects, based on 12,522 firm‐year observations from 1689 Taiwanese listed and OTC firms (2016–2023). The results show that family firms significantly underperform in overall ESG, particularly in social and governance dimensions, while environmental outcomes do not differ significantly. Higher blockholder ownership mitigates these disadvantages, especially in social and governance performance, and industry market concentration further attenuates ESG gaps across all dimensions. Bootstrap robustness tests confirm these findings. The study extends agency theory and socioemotional wealth perspectives by demonstrating how internal ownership structures and external market conditions jointly shape ESG outcomes in family firms, providing insights for governance practices and sustainability strategies in emerging markets.\n"]