This article explores factors that promote the practice of environmental citizenship in science education and aims to contribute to the development of the concept of practising environmental citizenship. We follow six Norwegian secondary students (aged 16-17) participating in a small-scale intervention study conducting an assignment on a socioscientific issue (SSI) in their local district. Our findings reveal that dealing with an SSI in real-world settings through out-of-school activities set in the students' local district is important for practising environmental citizenship. This article also addresses the tensions between the practice of environmental citizenship and the cultural issues related to school science. Our findings reveal that tensions exist between working with ready-made-science, as students normally do, to deal with science-in-the-making through an SSI. This research discuss the practical implications of the concept of practising environmental citizenship in science.