We examine how powerful CEOs affect stock price crash risk. We focus on family businesses in Vietnam because they contribute 25% of the national GDP. This study employs the Ordinary Least Squares and Fixed Effect Models and dynamic system Generalized Method of Moments to analyze a balanced panel of 983 annual observations of listed family businesses from 2005 to 2020. Our findings indicate that family businesses with CEO duality have about 60% higher crash risk than firms without CEO duality. However, higher CEO ownership reduces the stock price crash risk in the family businesses. The findings are robust after enacting the Law on Enterprises in Vietnam. Our findings align with agency theory, managerial power theory, information asymmetry theory, organizational theory, and prior literature. Our study contributes practical corporate governance implications for managing stock price crash risk in family businesses.