In the framework of a development cooperation program on quality of education in Vietnam, a professional development trajectory for teacher educators on the use of information and communication technology (ICT) in education was developed and implemented over the course of a three-year program. We describe how the framework on "Technological Pedagogical Content Knowledge" inspired the development of the program. In a longitudinal panel study, we followed a group of 1191 teacher educators (the "total accumulated population"). We describe the trainees' reaction to training and learning outcomes and we compare the use of ICT by educators who participated in the program with those who did not participate. Data was collected from self-reported questionnaires and focus group interviews. Comparison of the use of ICT for teaching over the course of the program shows that an ICT core group of enthusiasts made significant progress in integrating ICT into teaching practice. Exploratory multiple regression analysis highlights technological pedagogical knowledge and membership of a community of practice as significant factors for improved use of ICT. Nevertheless, the elements of the professional development program explain only 26.2% of variance. We discuss the extent to which programmed professional development can have an effect on integration of ICT in education and reflect on how to make training programs more effective. (Contains 5 tables and 1 figure.)