Few people would deny that initial and continuing teacher education are crucial factors in the improvement of education. Nevertheless, one must adopt a certain reservation before offering categorical and knee-jerk responses to the question which heads this article. This is not only a result of the ambiguity of the available evidence, so much the worse if one were to succumb to the temptation of establishing monocausal relationships, but also due to the very complexity of a question whose explicit and implicit terms (?improvement? and its conditions, the ?object? and the ?subject? of the same, the approach to professional preparation, etc.) are all debatable. Moreover, there needs to be some caution in examining the belief that it is feasibl...