In the present study, we aimed to compare reading-writing relations between first-grade Native English Speakers (NESs) and English Language Learners (ELLs). Thirty-four ELLs and 35 NESs completed measures of receptive and expressive vocabulary, lexical-level reading (word reading) and writing (spelling), and discourse-level reading (reading comprehension) and writing (written composition). After matching students on receptive vocabulary, differences in reading-writing connections were explored across lexical and discourse levels. We also examined the role of vocabulary knowledge in reading and writing performance. Results showed that word reading and spelling were significant predictors of written composition and reading comprehension, respectively, for both groups. However, reading comprehension and written composition predicted each other for the NES group only. Furthermore, vocabulary was predictive of reading comprehension and written composition only for ELL students. Findings highlight different patterns of reading-writing connections between NES and ELL first graders and underscore the importance of vocabulary knowledge in reading and writing for young ELLs.