Abstract Science teachers have often regarded in-service education as an ineffective way to improve their professional competence. At the same time a lot of resources are spent on in-service education, for instance in different project financed by the EU. This paper reports from a project with the aim to develop science teachers’ skills in inquiry based science education (“IBSE”) and assessment. In-service teacher education is provided by a series of workshops (24 hours in total). In order to investigate how the teachers perceived their development as professionals during the workshops, the teachers answered a questionnaire individually in the end of each series of workshops. The majority of teachers reported that they consider themselves as more experienced in teaching IBSE after the workshops; something they state will make them use IBSE and assessment more in the future. The results also indicate that teachers’ expectations of in-service education have been met by the workshops.