Adaptive learning technologies offer significant promise for bringing about fundamental improvements in education and training. For the past decade we have been investigating a family of intelligent game-based learning environments focusing on narrative-centered learning and integrating intelligent tutoring systems with game technologies. Research on these narrative-centered learning environments seeks to combine the inferential capabilities of user-adaptive systems and intelligent user interfaces with the rich gameplay supported by game engines. This line of investigation has the dual objectives of increasing learning effectiveness and promoting student engagement. In this talk we will introduce the principles motivating the design of narrative-centered learning environments, describe their roots in intelligent interactive narrative, and discuss ongoing work exploring their role in formal settings (K-12 schools, training) and informal settings.