The heterogenity of disorders covered by the term cerebral palsy (CP) may severely hinder communication between families on the one hand and health professionals, such as physiotherapists, paediatricians, and occupational therapists on the other. Common ground for communication about the child with CP is crucial for aspects such as diagnosis, treatment, care, management, and research. In his later work, Ludwig Wittgenstein introduced the concept of ‘language games’ (Sprachspiele) to underline that our use of language is permanently governed by rules, but not always by the same rules. On a daily basis we are involved in a large number of ‘language games’, where confusion and misunderstanding usually arise when a statement in one ‘language game’ is interpreted according to the rules of another. Speaking the same language, i.e. being engaged in the same ‘language game’ was one of the primary goals in the development of the Gross Motor Function Classification System, the recent redefinition of CP, as well as the recent development of the Manual Ability Classification System (MACS; also see Morris et al. p 950). This commentary focusses on the communication aspect of the MACS.