This article puts forward the case for the inclusion of sustainability as an element of teachers' professional digital competence. Following this, the article explores student teachers' reaction to a course on digital technologies and sustainability. An online survey was used to record the student teachers' reactions to the course and how they felt its content would influence their future actions. The student teachers had limited prior knowledge of the topic, but almost all acknowledged its importance, particularly in raising their awareness of global inequality. The student teachers reported they would change their purchasing habits, although some acknowledged that it would be difficult. Most believed it would influence their teaching, but perceived curriculum demands and school expectations tempered their expectations of what they believed they could achieve.