Background: Children with a significant cognitive and motor developmental delay are pre-symbolic communicators. The primary aim of this study was to reveal the variability within the communicative functioning of this group of children in terms of communication level, the reasons to communicate and behavioural expressions. Methods: Twenty-six children between 14 and 58 months with a significant cognitive and motor developmental delay were recruited. The Communication Matrix of Rowland (2011, "Communication Disorders Quarterly," 32, 190) was used to integrate different sources of information on the children's communicative functioning. Results: These children primarily communicated at the level of pre-intentional and intentional behaviour, aimed at refusing, obtaining and, to a lesser extent, social purposes. Conclusions: To develop or adapt early intervention strategies, and to monitor progress in communicative development, an even more nuanced view on these children's communicative utterances in terms of frequency, duration, idiosyncrasy and context relatedness is needed.