This article deals with the in-service training designed for teachers at different types of secondary schools which supported the teachers in putting a new curriculum into practice in a part of Germany (Lower Saxony). The teachers were asked to assess their competence in various fields of informatics before and after the in-service training. A significant increase in the teachers' assessment of competence could be determined. Moreover, the pre-existing differences in competence assessments between male and female participants could be reduced considerably after in-service training.