This paper describes the pilot of an interactional training programme designed for speech and language therapists to use with school support assistants, students and parents to enhance their implementation of therapy for children with speech sound difficulties. Collaborative therapy sessions in a school setting were videoed to encourage reflection on the participants' interaction using guided observation. Selected aspects of adult/child interaction were subjected to detailed conversation analysis and this showed that training resulted in positive changes in the therapy interactions including evidence of improved response outcomes for the children. The paper focuses on sequences where adult responses give the child further information about a prior attempt ("try") at a word as well as those that direct the child towards self-correction.