Running title: The handwriting brain of children Research Highlights • We used fMRI to uncover the brain correlates of writing acquisition and demonstrate that the network previously described in adults is also strongly activated in children. • However, group effects in the right cerebellum and left fusiform gyrus indicate that the network continues to mature between middle childhood and adulthood. • We also found group differences in prefrontal and precentral regions, which likely underpin changes in the control of writing with the acquisition of expertise. • These results fill a considerable gap in the field of writing acquisition. Abstract While the brain network supporting handwriting has previously been defined in adults, its organization in children has never been investigated. We compared the handwriting network of 23 adults and 42 children (8 to 11 year old). Participants were instructed to write the alphabet, the days of the week and to draw loops while being scanned. The handwriting network previously described in adults (5 key regions: left dorsal premotor cortex, superior parietal lobule, fusiform and inferior frontal gyri, and right cerebellum) was also strongly activated in children. The right precentral gyrus and the right anterior cerebellum were more strongly activated in adults than in children while the left fusiform gyrus was more strongly activated in children than in adults. Finally, we found that, contrary to adults, children recruited prefrontal regions to complete the writing task. This constitutes the first comparative investigation of the neural correlates of writing in children and adults. Our results suggest that the network supporting handwriting is already established in middle-childhood. They also highlight the major role of prefrontal regions in learning this complex skill and the importance of right precentral regions and cerebellum in the performance of automated handwriting.