We investigate mechanisms of institutional stability amidst profound environmental changes, using the case of corporate control in Japan. Over the last three decades, Japanese firms underwent a turbulent period with a series of crises. Throughout these crises, corporate leadership continued to be dominated by lifetime employees, despite the steady erosion of lifetime employment. Building on the concept of dualization from the comparative institutions literature, we theorize how dualized power relations at the top help sustain insider control—through the institutionalization of insider power and the circulation of different groups of outsiders. Our analysis, using data on all executive board members of TSE-listed firms from 1992 to 2016, demonstrates that executives who are lifetime employees at their companies continue to enjoy significant advantages in the contest for CEO succession. Lifetime executives maintain their dominance by promoting other lifetime employees while undermining the chance for others. In contrast, outsider executives, who joined the company as executive members and lacked durable intra-firm power bases, remain vulnerable to external changes. Our findings suggest that resistance by organizational insiders, combined with selective cooptation of outsiders, can help maintain institutional stability in a rapidly changing external environment. Lifetime commitment remains a valuable credential for CEO selection in Japan.