The recommendation is often that the teaching of environmental and sustainability education (ESE) or socio-scientific issues (SSI) in science should be interdisciplinary. One way of achieving this is to form multidisciplinary teacher teams. While the subject content may become more interdisciplinary, what about the outcome at student level? Research is sparse and there is a knowledge gap about differences in teachers’ teaching of ESE from different disciplinary traditions. This study investigates Swedish secondary teachers’ responses to a written enquiry that is designed to discern their teaching traditions, what they emphasise in their teaching. The results show that science, social science and language teachers stress some important educational aspects differently. Hence, without an explicit understanding of this among teachers unnecessary could result in unnecessary confusion for students or an educational content emphasizing limited types of different knowledge such as facts, attitudes or abilities.