Does using a computer game improve students' motivation to learn classroom material? The current study examined students' motivation to learn history concepts while playing a commercial, off-the-shelf computer game, Civilization III. The study examined the effect of using conceptual scaffolds to accompany game play. Students from three ninth-grade classrooms were assigned to one of three groups: one group used an expert generated concept map, one group constructed their own concept maps, and a control group used no map. It was predicted that the use of concept maps would enhance the educational value of the game playing activity, in particular students' motivational levels; however, the opposite happened. Students who used a concept map showed lower motivation on the task relative to their baseline motivation for regular classroom instruction. In contrast, the levels of motivation in playing the game, for students in the control group, met or exceeded their levels of motivation during regular classroom instruction. These results suggest that using a conceptual scaffold can decrease students' motivation to learn classroom material through game play, perhaps because conceptual maps can (a) focus students' attention on the difficulty of learning the concepts and on the extrinsic rewards for playing the game and (b) make game play less autonomous, less creative, and less active. All of these can negate the primary property that provides playing its principal potential pedagogical power: fun. (Contains 4 tables and 8 figures.)