This article explores the ways "gamification" can play a role in adolescents' development of vocabulary. Gamification involves the application of game-design thinking and play elements to non-game activities, such as routine homework or classroom lessons. Drawing upon data from in-school and after-school settings, the authors examine how eleventh grade students' use of adaptive online resources helped to support differentiated learning and improved understanding of vocabulary in context. Not only did students enjoy the adaptive and independent practices associated with a gamified approach to learning vocabulary, they also became more aware of their own word knowledge and developed a nuanced understanding of language.