To promote second language learning in dual-language learners, scholars have turned to media as a potential platform for L2 vocabulary development (Silverman & Hines, 2009; Wong & Neuman, 2019). At the same time, researchers in dual-language development debate whether using a child’s home language or L1 in instruction can facilitate dual-language vocabulary learning (Collins, 2010; Goldenberg, 2013; Lugo-Neris, Jackson, & Goldstein, 2010). The purpose of this study is to understand how providing children with the definitions of vocabulary words in their L1 might influence learning among Chinese preschoolers in the United States. More specifically, I use interviews to investigate the experiences of four preschoolers who are Mandarin-dominant and English-Mandarin-balanced as they view educational media in two conditions: English immersion and English immersion with Mandarin definitional supports. Findings demonstrate that when there were Mandarin (L1) supports, children could better recall plot episodes from the story, better understand English (L2) vocabulary words, and were cognizant of how the home language supported their learning. Implications for bilingual instruction in L2 development in early childhood contexts are discussed.