The aim of this article was to examine primary school teachers' perceptions about their sense of belonging in co-teaching. We were particularly interested in investigating the factors which enhance or hinder teachers' sense of belonging in their co-teaching relationships. The data were collected using the method of empathy-based stories (MEBS) consisting of frame stories with a variation in whether a co-teaching situation was experienced as positive or negative. Qualitative analysis of the stories revealed that teachers' sense of belonging was constructed through three dimensions: (1) teachers' work practices, (2) mutual relationship, and (3) individual characteristics. The findings contribute to the literature by demonstrating that a sense of belonging in co-teaching is a multidimensional phenomenon that is built in a close collegial relationship between teachers. The study adds a new micro-level perspective on how teachers' sense of belonging is constructed between two co-teachers.