This study shows how Developmental Work Research, an interventionist methodology based on Activity Theory, was used to develop collaborative working practice between teaching staff and a speech and language therapist in a school for children with special educational needs. The methods involved in Developmental Work Research are described, showing how they were adapted for this small-scale study from the original version described by Yrjö Engeström and his colleagues. The author describes the difficulties encountered, discusses how these were overcome and shows the benefits of using this approach. Some benefits found in this study were that participants became more aware of the roles and viewpoints of other team members, and solutions were created to some of the longstanding difficulties in their joint working practice. [This content is provided in the format of an e-book.]