It is established that transcription skills (handwriting and spelling) constrain children's writing. Yet, little is known about the mechanism underlying this relationship. This study examined the mediating role of bursts and pauses on the link between transcription skills and writing fluency or text quality. For that, 174 second graders did the alphabet task and wrote a story using HandSpy. Path analyses indicated that writing fluency and text quality models were excellent descriptions of the data, with 80% and 46% of explained variance, respectively. Results showed that handwriting and spelling influenced writing fluency only indirectly via burst length and short pauses duration (full mediation); and that whereas only handwriting contributed to text quality directly, both handwriting and spelling contributed to text quality indirectly, via burst length (partial mediation). These findings suggest that better transcription skills allow students to write more words without pausing, which in turn results in more fluent and better writing.