The ideology of one nation, one race, and one language has been constructed and reinforced in the Korean mind over the course of its history. However, a recently growing number of migrants in South Korea have challenged this ideology, and the Ministry of Education and Human Resources Development (MEHRD) announced the Educational Support Plan for Children from Multicultural Backgrounds (ESP) in 2006 to address the needs of multicultural children in schools. Under this initiative, the national curriculum was revised to raise the understanding of diverse cultures among all students, and textbooks were developed under direction from MEHRD. Taking a critical perspective toward language policy, the current study aims to offer a historical account of the emergence of monolingual ideology in South Korea and then to analyze how this ideology has shaped recent multicultural education policies.