Although policy documents emphasize the importance of integrating social, economic, and environmental dimensions into education for sustainability (EfS), there is a lack of studies investigating how social sustainability can be included in preschool teaching. Therefore, this study aims to increase knowledge about preschool teachers’ teaching practices relating to social sustainability. This study uses EfS as a conceptual framework that includes a holistic view of sustainability addressing social, economic, and environmental aspects, as well as pluralistic teaching approach from a transformative perspective. To explore the views and teaching practices, individual interviews were conducted with 12 preschool teachers from eight preschools that took part in a school development project. The project included professional development workshops for teachers on EfS and local implementation efforts. Thematic content analysis was conducted. The interviews made it apparent that the teachers initially viewed sustainability from an environmental perspective; however, after involvement in the school development project, they began to integrate the social sustainability dimension into their teaching. The teachers associated local sustainability challenges with those faced internationally. To a certain extent, children’s agency was noted in pluralistic educational activities that supported children’s active participation. The level at which preschool teachers integrated social sustainability into their teaching varied.