This paper examines the school-wide introduction of the tablet computer as a mobile learning tool in a secondary school in Belgium. Drawing upon the Decomposed Theory of Planned Behavior, we question during three waves of data collection which factors influence teachers' and students' acceptance and use of these devices for educational purposes. The first wave indicated that attitudes towards the rollout are generally positive. Teachers and students are intrinsically motivated, welcoming it as an instrumental, and for students enjoyable, learning tool. However students do report feelings of social pressure. While after three months, the prior expectations hold up for both stakeholders, results of the third wave show a different pattern. Teachers' acceptance seems to be related to attaining a positive attitude, social influence and the sense to master the new technology while regarding students' results; only behavioral control remains significant. These results challenge teaching practices and invite manifold areas for further research.