In France, a quarter of pupils change schools during their elementary education. In this article, we analyse families' motives in changing schools. Using a rich longitudinal database, we distinguish different motives for mobility: strategic mobility (search for a better school), reactive mobility (due to school difficulties) and residential mobility (due to a move). These different mobilities concern different academic and social student profiles. We then examine the extent to which school mobility influences later school performance. Using matching methods, we show that mobile pupils have significantly higher academic achievement than non-mobile pupils at the end of elementary school. These results are nevertheless heterogeneous with a neutral influence of strategic mobility, a negative influence of reactive mobility and a positive influence of residential mobility.