Top managers hold a significant position in the functioning of public organizations. While existing studies have predominantly investigated impacts of individual characteristics of top managers on public organizational outcomes, limited attention has been given to heterogeneity, especially non-demographic heterogeneity, among them. This study focuses on the impact of language dissimilarity among top managers in public organizations and proposes that the dissimilarity can negatively influence their communication and social identification, leading to a decrease in organizational performance. Based on economic growth and managers’ biographical data across cities in China (N=4700), our two-way fixed effects model finds that the language dissimilarity between the two top managers in a city government has a negative impact on the economic growth rate of the city. This impact does not diminish as the two managers work together over a long period, and the ethnic dissimilarity between them can amplify the negative impact. Our findings highlight the pivotal role of top management team’s heterogeneity in driving the performance of public organizations.