Executive functions (EF) refer to self-regulative processes that underlie goal-directed activities. While previous research has shown a strong relationship between EF and achievements in school, there is a paucity of empirical research that has examined how EF contribute to writing development in the upper elementary grades. This longitudinal study examined how EF predict development in narrative writing in these grades. Both in fourth and in sixth grade, children’s writing skills were assessed using a narrative picture-elicitation task. In addition, in fourth grade a battery assessing transcription skills, language skills, and EF was administered. The results showed that in fourth grade, EF contributed directly to the quality of the written narrative, and indirectly, with handwriting fluency functioning as a mediator. Furthermore, results revealed that EF in fourth grade predicted development of the syntactic complexity of the written narratives between fourth and sixth grade. The theoretical and educational implications of these results are discussed.