In recent years, there has been a growing interest in pre-school children's meaning-making and learning in education for sustainability. Young children should be recognized as "agents for change" and active participants in their own day-to-day practices. Such issues are thoroughly discussed in the early childhood education for sustainability field. However, only a few research reports are presented on the subject. In this paper, our purpose is to examine empirically how agency is constituted when pre-school children explore science-related issues in a context of education for sustainability. The empirical material consists of video-recording sequences of four- to five-year-olds. In the analysis, we use a methodological approach based on Dewey's pragmatist philosophy. We describe what a small group of children are doing and their "course of action" towards "fulfilment". In view of this, agency is explained as something that children achieve together in transactions rather than something they possess. Furthermore, the findings show the significance of the aesthetic relations in the constitution of agency. At the end of the article, we also discuss agency in relation to the ongoing debate on participation in young children's meaning-making for sustainability.