The impact of an Education for Sustainability (EfS) course for science and technology junior high school teachers on the intentional and actual environmental behaviour of participants was studied by researching the EfS implementation of 13 science and technology teachers within their family, community, and work environment. The research was qualitative in nature, where science and technology teachers' insights on the EfS course were determined by means of an open-ended questionnaire and intensive interviews. Results indicated that the course clearly influenced the vast majority of the participants, who claimed that their environmental awareness had increased and they were capable of acting responsibly. All participants acted in favour of the environment among family, community, and at work. Yet, 2 years later, implementation seemed to be undermined by various internal and external barriers, such as the unavailability of convenient resources, or resistance on the part of family. The study suggests that course designers must include reference to potential difficulties and barriers in order to circumvent future obstacles. In addition, the implementation of post-course support would encourage overcoming the gap between willingness to act and actual practice.