In this Chapter, we explore what is at stake for university students when negotiating a geoscience identity in relation to the process of establishing disciplinary knowledge. We use the concept of science identity to understand how the students are recognised and how they negotiate their competence and belonging in learning situations within the discipline of geology. By utilising ethnographic methods, we study students’ learning processes in different fieldwork settings. The analysis shows how science identity within a discipline takes many forms, both visible and tacit, and for the students it requires identity work in relation to performing in specific ways in order to be recognised as competent within the discipline. The chapter demonstrates how studies of the relations and intersections between the concepts of sense of belonging, disciplinary culture and tacit knowledge in concrete learning situations can help us unfold students’ identity work when establishing their disciplinary knowledge. As such, the chapter adds to the research field of science identity by bringing in the context of the discipline and how it intersects with the students’ negotiations of belonging in the disciplinary culture.