There is much research into teachers' workplace wellbeing, but very little research investigating teacher assistants' wellbeing in the workplace -- especially those who work in classrooms where students with a disability are present. Research among teachers has identified adaptability as a key to their workplace wellbeing. Following this research, among a sample of 128 teacher assistants who work in classrooms where students with a disability are present, we explored four workplace wellbeing outcomes (workplace enjoyment, participation, self-concept, and motivation) and the role of adaptability in predicting these wellbeing outcomes. Hierarchical path analysis showed that teacher assistants who were adaptable demonstrated significantly higher workplace enjoyment, participation, self-concept, and motivation. Findings suggest workplace adaptability as a critical element of workplace wellbeing for teacher assistants who support students with disability.