This paper presents findings from an empirical study that investigated the learning experiences of deaf students in mainstream secondary classrooms, from teaching assistants' (TA) perspectives. These findings indicate that effective collaboration between mainstream teachers and specialist teachers of the deaf (ToD) is required to ensure appropriate expectations of deaf students to support improved outcomes. A qualitative, collaborative methodology was developed that facilitated a trustworthy approach to the collection of data to represent TAs' perspectives. The participants comprised 10 TAs, 5 mainstream teachers, 7 deaf students and 3 ToDs. Each TA had a minimum of three years' experience supporting deaf students in mainstream classrooms. The TAs discussed their experiences in focus group discussions and semi-structured interviews. Interview data, generated by the other participants, served to validate the TAs' perspectives of their working contexts. Consideration was given to how the TAs talked about learning and the challenges they perceived deaf students encountered, with particular emphasis on specialist knowledge and working relationships in the classroom. The TAs were explicit in their belief that mainstream teachers were frequently unaware of the challenges many deaf students experienced. Analysis revealed the degree of collaboration between mainstream teachers, ToDs, TAs and deaf students, and the limited extent to which specialist knowledge informed pedagogical and support practices.