In the 1990s, courses on sustainable development (SD) were introduced in technological universities. After some years of practice, there is increased interest in the evaluation of the most effective ways for teaching SD. This paper introduces the use of conceptual maps as a tool to measure the knowledge acquired by students when taking a Sustainability course. Pilot measurements have been made to evaluate the concepts and their interrelations in order to evaluate the students' learning. These measurements were carried out using a sample of more than 700 European students. To measure the learning outcomes of courses, the evaluation is done twice. Before the course starts, the students' previous knowledge on sustainability is measured; once the students have completed the course they are evaluated again. By comparing conceptual maps drawn by each student, the improvement of the students' knowledge is evaluated. This paper shows the measuring process, and points out the suitability of using conceptual maps for research in education. Moreover, the correlation between the learning outcomes the pedagogical techniques used in each course may indicate the effectiveness of the pedagogical strategies in education for sustainable development. (Contains 3 tables and 3 figures.)