Intensive Interaction is an approach to enhancing the communication and social abilities of people with profound intellectual disabilities using principles from caregiver-infant interaction. Use of Intensive Interaction by novice practitioners with four women with profound intellectual disabilities living in a supported housing service in England was evaluated. It was hypothesized that staff could learn the principles of Intensive Interaction sufficiently to have a positive impact on the participants' abilities (during five sessions per week over 20 weeks) and that they would experience a better relationship. A quasi-experimental interrupted time-series multiple-baseline design was used with data collected via video observations, assessment schedules and staff questionnaires. Practitioners learned to use mirroring and contingent responding, and participants' abilities to look at faces and become engaged in interaction and joint focus developed. There was less volume of evidence for improved quality of relationship. Embedding practitioner reflection on interactions was a difficult part of the intervention to implement.