Michael Young, P. G. Schrader, and Dongping Zheng use the concepts of ecological psychology to examine how massively multiplayer online games (MMOGs) promote specific learning processes in their players. In their analysis they identify and define nine principles of learning that allow such games to have valuable potential as tools for educators: the perception-action cycle, embodied cognition, social attributes of situated learning, boundary constraints on behavioral trajectories, affordance-effectivity duals, goal-directed action, contextualized learning, repetition, and detection of the raison d'etre. They then provide examples of these principles in the case of two MMOGs--"The Sims Online and Quest Atlantis"--in order to illustrate the potential of this technology to enhance student learning in educational contexts. (Contains 3 exhibits and 3 figures.)