Multilingual education has gained recognition for its cognitive benefits, yet implementation strategies vary significantly across cultural contexts. This longitudinal study tracked cognitive development in 456 students across monolingual, bilingual, and multilingual educational programs over three years. We assessed executive function, creative thinking, and metacognitive awareness using standardized instruments and novel linguistic tasks. Results reveal superior performance in multilingual students across all cognitive domains, with effect sizes ranging from 0.45 to 0.78. Notably, students maintaining heritage languages alongside international curricula showed enhanced cultural competency and academic achievement. The research provides evidence-based recommendations for multilingual program design and teacher training.