This qualitative study investigates immigrant mothers' beliefs and practices toward supporting maintenance of their children's heritage language (HL) in the context of transnationalism. The data are primarily drawn from formal and informal interviews and observations of six mothers who immigrated to the United States from Japan and Korea. The findings demonstrate that the immigrant mothers view their children's HL maintenance as a bridge that connects intergenerational families across countries, and as a positive asset that will open up academic and career opportunities for their children in the future. Nevertheless, challenges in maintaining a balance between HL and English were noted. The participants shared three transnational strategies to support HL maintenance, including (1) use of transnational media to teach cultural knowledge and to motivate HL learning, (2) frequent visits to home countries for children to participate in public schooling, and (3) using print and literacy resources in HL that were imported from their home countries. This study calls greater attention to immigrant mothers' transnational knowledge and networks as valuable resources for their children's HL learning. The findings also demonstrate the necessity of examining immigrant children's language learning experiences that traverse across geographical boundaries.