Critical to the success of creating a high-quality game-based learning environment is the process of iterative refinement that begins with design, proceeds to development, continues with implementation, and then repeats the cycle with lessons learned from each successive deployment. The CRYSTAL ISLAND: UNCHARTED DISCOVERY learning environment has undergone a ser- ies of iterations, each stage of which has incorporated feedback obtained from student and teacher interactions with the sys- tem. It is important to note that although this article is limited to research conducted in the United States, CRYSTAL ISLAND has also been implemented with students and teachers in classrooms in China and New Zealand. Over the course of four years, the project included three phases: (a) pilot study, (b) experimental field tests, and (c) an integrated classroom deployment to initiate a shift towards ecological validity.