We discuss a component-based, developmental view of text writing fluency, which we tested using data from children in Grades 2 and 3. "Text writing fluency" was defined as efficiency and automaticity in writing connected texts, which acts as a mediator between text generation (oral language), transcription skills, and writing quality. We hypothesized that in the beginning phase, text writing fluency would be largely constrained by transcription skills (spelling and handwriting), while at a later phase, oral language would make an independent contribution to text writing fluency. Furthermore, we hypothesized that text writing fluency would have a stronger relationship with writing quality at a later phase than at an earlier phase. We operationalized text writing fluency using two curriculum-based measurement writing scores: percentage correct word sequences and correct minus incorrect word sequences. Results revealed that in Grade 2, only transcription skills were uniquely related to text writing fluency, whereas in Grade 3, oral language was also related to text writing fluency. Text writing fluency was weakly related to writing quality in Grade 2 but strongly related to writing quality in Grade 3, over and above oral language and transcription skills. In both grades, oral language and handwriting fluency were independently related to writing quality. Theoretical and practical implications are discussed.