ABSTRACTThis article analyzes the effects of firms’ founding ownership in shaping their corporate social responsibility (CSR) performance in China. Drawing on a nationwide survey of 1,037 representative manufacturing firms in 12 cities, we specify the imprinting effects of firms’ founding ownership on labor and environmental protections, two important CSR practices. Our results show that state-owned enterprises (SOEs) founded during the state socialist period, regardless of their restructuring experience in the market reform era, continued to implement pro-labor practices. Moreover, even the SOEs founded in the market reform era provided better labor protection than non-SOEs founded during the same time. In contrast, the founding imprints of environmentalism in the reform era for non-SOEs, especially thede novoprivate firms, explain why they spent more than SOEs in environmental protection. We extend the organizational imprinting theory by highlighting the importance of firms’ founding ownership imprints and in shaping their current CSR performance.