We provide a robust measure of isomorphic behaviors of corporate social responsibility (CSR) practices by using Latent Dirichlet Allocation (LDA) topic model to uncover the informational content within CSR reporting, which is a comprehensive document that outlines a company's efforts, strategies, and performance related to social, environmental, and governance responsibilities. Focusing on state-owned enterprises (SOEs), we investigate whether these firms exhibit more homogeneous CSR practices compared to non-SOEs, in response to institutional pressures. In line with institutional theory, our analysis reveals that SOEs are more likely than non-SOEs to align their CSR practices with those of peer SOEs from the previous year in pursuit of legitimacy. This tendency is especially pronounced in pollution-intensive industries and firms under mimetic and normative pressures. Furthermore, we find that geographical proximity and board interlock networks are two mechanisms facilitating the dissemination of CSR-related information. Our results hold under a series of robustness and endogeneity tests.