Résumé : In this paper, we present I-FLEG, a serious language game designed for interactively learning French as a second language. The game is integrated in Second Life and exploits the 3D virtual reality environment provided by this platform to implement immersive, learn-by-doing techniques that have proved to be among the most effective learning strategies in second language acquisition. Furthermore, the integration of the game in Second Life permits to fulfill many important desiderata of computer-aided learning technology. It allows ubiquitous, long distance learning as well as universal access. In addition, these characteristics by facilitating the collection of big amounts of test data over the web render our game an ideal device for both monitoring learner performance in dependence on situational context factors and for comparing different teaching technologies.