How do engineering students develop a professional identity during the course of the curriculum? What are the development mechanisms and important conditions? In an exploratory study among teachers the authors tried to find out whether the development of engineering identity can be understood by using the theoretical models of Ibarra and Sullivan. The results showed that the development of engineering identity is boosted during the internship in industry in the third year. Furthermore, the theoretical models could be recognised in the findings and four interaction types in internships, with significant differences in effect on identity development, could be identified if two dimensions were used: (1) industry supervisors' perception of students; (2) the professional responsibility awarded. Some recommendations for curriculum improvement could be made; for example, introducing projects into the curriculum to stimulate identity development from the start. Further research is required on students' preparation for internships. (Contains 1 table and 1 note.)