Recent changes in German national standards and curricula have made statistics including digital tools an inherent part of the final examination at upper secondary schools. In previous years, many teachers focused only on mandatory content like algebra or analysis and almost completely avoided optional stochastic content. Thus they are now facing the challenge to create and implement lessons for a topic in which they are inexperienced and feel insecure. The professional development course presented in this study has the aim to increase teachers’ knowledge and competence in statistics, including the use of digital tools like graphic calculators and GeoGebra. A newly developed questionnaire was used to assess teachers’ development during the course and led to preliminary findings concerning the knowledge and competence for advanced topics of inference statistics and the expertise of using digital tools in this field.