This study comparatively analyzes census language questions across four multilingual societies—Canada, the United States, Singapore, and South Africa—to examine language ideology-policy interactions. Using Language Management Theory (LMT), the research employs content analysis, discourse analysis, and cross-national comparison of census questionnaires, policy documents, and media texts. Key findings include: (1) Census language questions evolved from monolingual assumptions to multilingual recognition across all countries, with documented policy-census cyclical relationships; (2) Census design systematically reflects and reinforces language hierarchies while facing representational limitations in capturing multilingual realities; (3) Cross-national comparison reveals four distinct language management models: institutional bilingualism (Canada), pragmatic monolingualism (United States), strategic multilingual management (Singapore), and aspirational multilingual equality (South Africa); (4) Media discourse functions as an intermediary mechanism between census data and policy development, consistently interpreting demographic statistics and framing language policy debates across different national contexts. The study validates Language Management Theory's cyclical framework in institutional settings and provides practical recommendations for more inclusive census design and language policy formulation.