In subject teacher education, the main issues in sustainable development education (SDE) lie in questions as to what the educators are supposed to teach, what the status of subject teacher education is today in embedding SDE, and how SDE relates to the focus on professional competencies in teacher education. The aim of this study is to investigate the subject student teachers’ views on their social competencies in teaching students about sustainable development (SD) with respect to local, regional, and global environmental issues. The study questions were: (1) What kind of environmental problems do the students regard as core environmental problems—locally, regionally, and globally? (2) What kind of opportunities do the students feel they have to socially influence local, regional and global environmental issues? (3) How do the students identify and understand the social relationships in the classroom? and (4) How do the students see their likelihood of influencing the school culture they are working in with respect to sustainable development? A total of 142 subject student teachers at six Finnish universities were surveyed. The material was collected using a web-based questionnaire and analyzed by inductive content analyses based on two factors: (1) the multidimensional adapted process model of teaching, especially regarding teachers’ social competences and (2) the competences in SDE. The results showed the students are concerned about issues such as climate change and littering, and would address these by reasonable knowledge construction and social means. In the school environment, the students are interested in SD decision-making, and they value equality and the mental well-being of students, which are supported by the quality of education goals, especially Sustainable Development Goal 4 (SDG4). The findings are discussed with respect to the social skills introduced in the multidimensional adapted process model of teaching, in particular with respect to the UNESCO’s listed competencies in teaching and learning about SD.