Pinyin is a sound-annotating system for Chinese characters using Roman letters. Teaching and learning Pinyin has been an important educational practice in Mainland China for native Chinese children, and it is also typically taught to beginning learners of Chinese as a foreign/second language in tertiary-level classrooms. However, whether it should be taught to nonnative children who are studying Chinese as a second language has been controversial. This study examined the roles of Pinyin skill in Chinese-English biliteracy learning among a group of second-grade learners in a Chinese immersion program across one academic year and found that Pinyin facilitates subsequent Chinese word reading at no cost to students' English literacy learning. Results are discussed in the context of learning Chinese as a nonnative language among young learners in school settings. Implications for teaching Chinese reading, curriculum, and material design, especially for Chinese immersion programs, are discussed.