Many students arrive at middle school without the academic language skills they need to read sophisticated texts with comprehension. In particular, English language learners and students from low-income backgrounds attending underresourced, urban middle schools lack opportunities to learn the thousands of academic words they need to succeed. To build their comprehension, teachers must not only teach the meanings of specific vocabulary words, but must also equip students with tools to be active word learners. This article presents a research-based approach to improving adolescents' word-learning abilities by building their understanding of morphology. (Contains 2 tables and 3 figures.)