The aim of this study is to describe interaction between mothers/ caregivers and their profoundly mentally retarded and multiply handicapped children, and to describe the function of play in communicative interaction. In the study I describe the communicative interaction of six children aged 1:3 to 10 years. The children have been studied in their homes and preschools or schools. Each child had five or six handicaps in addition to their profound retardation. The study is based on interviews with parents, information from naturally-occurring conversations and videoobservations. Meals and play were selected for video-recording. The results indicate that the most important function of play is as a means of communication and learning. Play most often involves sensory stimulation and body play. Communicative interaction is non-verbal and described in terms of gaze/eye contact, facial expressions, gestures and body movements. A pattern of interaction has been found. This consists of four phases: an impression-receiving phase with orientation, an expressive phase with motor activity, a pause with processing and preparation of an answer and finally a break or a limited reaction. These children have, however, a communicative competence. The ability of the mothers to interpret the children’s signals is extremely context-dependent. These mothers adjust their communicative behaviour to the child and facilitate the child’s communicative interaction. The ability of the mothers/ caregivers to interpret the signals of these children is often underestimated by professionals. The living conditions of the parents have emerged as an important factor for play, communication and the development of the child.