Morphological awareness has been shown to contribute to the acquisition of literacy in various languages. The current study focuses on an explicit derivational morphology training program in French-speaking fourth graders with the aim of measuring direct effects on morphological awareness and transfer effects on spelling and reading. The intensive training given in class consisted of (1) learning how to segment words into smaller units and (2) understanding the meaning of affixes in relation to words. Thirty-six children received the morphology training and 34 age-matched participants followed an alternative visuo-semantic training matched for intensity. The results of this pre-post group comparison study show a significant Group by Time interaction: Substantial progress in morphological awareness is observed for the group trained in morphology, on both trained as well as on untrained items. A similar gain was observed for the spelling of morphologically derived words, for trained and untrained words. Both roots and affixes were spelled more accurately. For reading however, we found a learning effect in speed and accuracy on trained words, but no generalization to untrained words. All effects were maintained four months after training. These results highlight the role that morphology plays in children’s literacy development.