Learning to write is one of the great challenges children face in primary grades, requiring both transcription skills (handwriting and spelling) and executive functions (EFs; working memory, inhibitory control, and cognitive flexibility). Although this claim is widely accepted, the field suffers from some limitations, including few longitudinal studies examining the joint role of transcription and EFs in the writing of school-age children. The current study aimed to fill in this gap with a twofold goal: to examine the development of transcription and EFs in Portuguese children transitioning from primary (Grade 4) to intermediate school (Grade 5); and to evaluate the longitudinal and concurrent links between transcription and EFs to text quality. The sample included 222 Portuguese students in Grade 4, who were reassessed one year later, in Grade 5. Results showed significant improvements from Grade 4 to 5 in handwriting and spelling as well as in verbal working memory and cognitive flexibility. Moreover, though spelling and cognitive flexibility in Grade 4 had longitudinally predicted text quality in Grade 5, these links disappeared when Grade 5 predictors were considered. In the final model, only transcription skills along with cognitive flexibility and inhibitory control in Grade 5 were significant predictors of text quality in Grade 5. These findings show that transcription and EFs play a role in writing and suggest that this role might be more concurrent than longitudinal.