This research describes the development and validation of an instrument to measure integration of Information and Communication Technology (ICT) in education. After literature research on definitions of integration of ICT in education, a comparison is made between the classical test theory and the item response modeling approach for the development and validation of a questionnaire. Following the last approach, a construct on integration of ICT is developed, items are generated and an outcome space of Likert type answering categories is defined. The resulting questionnaire has been administered to 933 teacher educators. In this study the collected data are tested for fit to the Rasch model of measurement. It is concluded that the instrument can be used for fundamental measurement of perceived use of ICT for teaching and support of student learning of the reference population, allowing for identification of stages of innovation of ICT integration. We reflect on the critical value of the item response modeling approach and the Rasch measurement model for measurement of integration of ICT in education and discuss some limitations of the study. (Contains 4 tables and 4 figures.)