We studied 1) how pre-service language teachers reacted to the assumption that they should acknowledge sustainable development in language teaching, 2) what considerations they gave to sorting sustainability themes based on their importance, and 3) what themes they considered easy, hard, familiar or unfamiliar to integrate into language teaching and why. We analyzed two questions from a sustainability themed questionnaire considering all dimensions of sustainable development and the group reflections of the pre-service language teachers directly after they had answered the questionnaire. The pre-service language teachers considered sustainable development to be of high importance but were concerned about whether they are qualified to include it in their teaching, and whether they have enough time for it. Based on our results, pre-service language teachers would benefit from schooling in sustainability education, and handling global and local issues separately could help them to better understand sustainability themes.