Although fluency and automaticity of handwriting have been recognized as important research topics for 30 years, empirical data on respective developmental courses among typically developing children as well as clinical samples have remained very limited. To fill this gap, this study investigates the development of handwriting automaticity employing a longitudinal design, including monthly measurements over a period of six months for 48 kindergarten and school-aged children (first and second grades) in Switzerland attending school-based graphomotor therapy for handwriting difficulties. Handwriting automaticity is operationalized as the number of inversions of velocity measured during the completion of specific tasks on a graphics tablet. The results reveal different improvement patterns over time depending on the tasks to be completed. The clinical implications of the results are discussed.