Teachers are likely to work with teacher assistants throughout their careers, yet they are often not provided with opportunities to learn how to gain maximum benefit from having an additional adult in their classroom. Teachers frequently report a lack of clarity with regards to the most effective way to collaborate with teacher assistants. The problem could be compounded even more in secondary classrooms. Unlike the majority of the past research where the focus is on teacher assistants, in this study we interviewed sixteen secondary school teachers in the state of Victoria, Australia, to gain an insight into their experiences working with teacher assistants and the factors that facilitate or impede their practice. Data were analysed using Braun and Clark’s (2006) process to establish key themes. A number of factors were identified that have relevance to how to fully support and empower secondary school teachers to effectively work with teacher assistants. The research has implications for teacher educators as we report about how universities can best prepare pre-service and in-service teachers to enhance their capacity to effectively work with teacher assistants. The results of this study also prompt schools to reconsider their models of support for students with disability when employing teacher assistants.