This study surveyed Finnish subject student teachers’ views on their competen- cies in environmental issues in sustainability education (SE). The study questions were as follows: (1) Which competencies were demonstrated in the respondents’ answers concerning the environmental problems that they mentioned?; (2) How do the answers reflect the eight key competencies for SE?; and (3) How do the answers differ between the groups of subjects with respect to the competencies displayed? A qualitative content analysis was carried out by focusing on the res- pondents’ competencies in SE (n = 138). Of the eight competencies defined by UNESCO, seven were found in the answers. The most common were collaboration, integrated problem solving, and strategic thinking. The least common were the normative, critical, and systems-thinking competencies. While the prevalence of the key competencies mentioned in the answers varied, there was no systematic or thematic difference between the different subject groups. The findings indicate that the practice of cultivating self-reflective competencies in teacher education is important for a future teaching career.