Questions about how best to deploy teaching assistants (TAs) are particularly opposite given the greatly increasing numbers of TAs in British schools and given findings about the difficulty effecting adult teamwork in classrooms. In six classrooms, three models of team organisation and planning for the work of teaching assistants -- "room management", "zoning" and "reflective teamwork" -- were evaluated using a repeated measures design for their effects on children's engagement. Detailed interview feedback was also gained from participating teachers and assistants about the perceived benefits of each model and possible adaptations to the models for future classroom use. All three models were found to effect significant improvements in engagement in all of the classrooms, and each was evaluated positively by participants, with useful commentary concerning adaptation.