This study examines the challenges of minority language transmission in exogamous families in a society where linguistic and cultural homogeneity still prevails. Specifically, it investigates the macro and micro ideological influences that lead multilingual migrant mothers in Japan to speak Japanese to their children. Interview data with six Thai mothers revealed that political influences made them emphasize the learning of Japanese. Economic factors led to the mothers' valorization of Japanese, and even English, and lackadaisical efforts toward developing their children's Thai. Sociocultural influences contributed to their practice of speaking Japanese to their children in front of Japanese speakers. The mothers' childrearing experiences also affected their language practices. Their perception that Thai exposure delayed their older children's Japanese development led them to use more Japanese to their younger children. The mothers' limited use of Thai led to a lack of comprehension and low production of Thai by their children.