Given that input-based language and literacy environments provide socioculturally-enriched contexts for bilingual and biliteracy acquisition, the current study aims to explore the contribution of early input in various sociocultural contexts to later biliteracy development among ­college-level Chinese heritage language (CHL) students. A group of CHL students (N = 195) participated in this study and completed a background survey about their early oral and print experiences in different sociocultural contexts. Biliteracy measurements including Chinese-English bilingual morphological awareness and reading ability were administered to the participants. Drawing on multivariate analyses, the study verified both intralingual and interlingual contributions of input-based experiences to biliteracy development. The study suggests that (1) community and after-school language and literacy support can have a long-term impact on the maintenance of heritage language literacy skills. (2) heritage language input experiences do not create obstacles for dominant language literacy development. (3) heritage language literacy input provides facilitations for the abstraction of bilingual structures and units.