In this study, we elicited grammatical forms (oral production) from a group of child heritage speakers of Spanish (N = 45) in English and Spanish, using the morphosyntax subtest of the Bilingual English-Spanish Assessment (BESA), (Peña et al. 2014). A cross-sectional design was used with 25 participants in kindergarten and 20 in first grade. All children spoke Spanish at home and attended English rural schools. We controlled for L2 class environment and socio-economic status. Research findings indicated children produced more target structures in L1 Spanish. This project supports the view that sequential bilingualism and continuous exposure to the heritage language may assist heritage speakers to maintain some L1 structures (Miller and Cuza 2013; Pascual y Cabo and Gómez Soler 2015). Patterns of L2 development are also addressed.