The aim of this study was to examine the contribution of teachers’ initial training (field of study, attending education for sustainable development (ESD) course/s) as well as student teachers’ socio-demographic characteristics (gender and age) to their readiness to implement ESD (intention to implement ESD and teachers’ self efficacy). A total of 706 student teachers studying at six Croatian universities participated in the study. It was determined that female student teachers express greater intention to implement ESD, however the gender differences were not found on teachers’ self-efficacy for ESD. Furthermore, the older the participants, the lesser the extent to which they express their intention to implement ESD. Student teachers in the field of the natural sciences express the intent to implement ESD to a lesser extent compared to students from other fields (humanities, arts, and social sciences). Lastly, it was determined that student teachers who have attended ESD course/s express higher levels of intention to implement ESD as well as teachers’ self-efficacy for ESD. In that sense, the higher the number of attended ESD courses, the higher student teachers’ readiness to implement ESD. Based on the results of this study, recommendations for teacher education programs have been offered.