Many authors have claimed that participatory perspectives should be a significant feature of environmental and sustainability education (ESE). This change in ESE practice implies a relocation of the process of environmental knowledge constitution from ‘before’ to ‘in’ the educational event. The aim of this paper is to clarify both the processes of knowledge constitution and the content of the constituted knowledge within participatory ESE practices. Two methods based on John Dewey’s transactional perspective are used in the study: epistemological move analysis and pragmatic discourse analysis. The empirical material consists of video-recorded student discussions about climate change in the setting of a Swedish upper secondary school with a pronounced sustainability approach. In the analyses, six different epistemological moves used by the students are identified. The analyses show how students cooperatively constitute a specific view of climate change by using these moves. A main conclusion of this study is that participatory approaches do not necessarily mean that knowledge becomes more diverse. It is therefore important that teachers pay attention to governing processes among students and occasionally challenge the common view in order to allow for alternative possibilities and views.