Cognitive and linguistic components related to spelling and writing in English as a second language (ESL) and native-English speaking (EL1) third graders were examined. ESL and EL1 children performed similarly on rapid naming, phonological awareness (PA), verbal short-term and working memory, reading fluency, single-word spelling, text spelling, handwriting fluency, and paragraph writing fluency tasks, and on writing quality indices. ESL children scored lower on vocabulary, syntactic awareness and decoding fluency measures. PA predicted single-word spelling for EL1 and PA and rapid naming predicted single-word spelling for ESL. PA and rapid naming contributed to text level spelling across groups. Rapid naming and syntactic awareness predicted writing quality (content and structure) for ESL children, but syntactic awareness and oral vocabulary predicted writing quality for EL1. Transcription predicted overall writing achievement for ESL, but transcription, vocabulary, and syntactic awareness were all important to overall writing ability for EL1. Results are discussed in relation to the componential model of writing in a first or a second language.