Research on adult writers has shown that writing proceeds through bursts of transcription activity interspersed by long pauses. Yet few studies have examined how these writing behaviors unfold during early and middle childhood. This study traces the progress of bursts, pauses, transcription, and written composition in Portuguese students from Grade 2 to 7 and tests whether bursts and pauses are related to transcription, to writing fluency, and to text quality across grades and two genres (narrative vs. opinion essay). We found that increasingly automaticity of transcription allowed for more efficient composing processes, as reflected in longer bursts, shorter pauses, and greater fluency. Regardless of grade and genre, more automatic transcription contributed to longer bursts, which along with shorter pauses contributed to higher writing fluency and text quality. These results provide useful information on children's language bursts and pauses, which may support the assessment and further training of their writing skills.