In the Netherlands, many educators and care providers working at special schools for children with severe speech and language impairments (SSLI) use sign-supported Dutch (SSD) to facilitate communication. Anecdotal experiences suggest positive results, but empirical evidence is lacking. In this multiple case study the changes that occur in the way children with SSLI (n = 8) communicate after SSD is offered to them in an educational setting were explored. Video-recordings of teacher-student interactions were made at two-month intervals, starting with a baseline observation followed by six months of SSD input. The samples were analysed for mode of communication, and special attention was given to the gestures and signs used by the children. The way in which the children supplemented or replaced speech with hand movements, and the frequency in which they did so, varied and seemed to be associated with the form of their underlying speech problem. After six months of SSD input, the children did use early gestures more frequently, although they rarely used signs.