People with congenital deafblindness (CDB) are a heterogenic group, and CDB is defined in a variety of ways in the scientific literature. In this study, we aim to examine whether some of the heterogeneity may be more easily resolved from the perspective of ability than from the perspective of impairment. In order to do this, we take as a starting point for our investigations the communication systems that are used and the different sense modalities they require. Information about almost the entire known population of children with CDB in Denmark (age = 3–18 years, N = 71) was collected using a questionnaire form, covering degree of visual and hearing impairments, intellectual disability, level of expressive communication and use of communication systems. No correlation was found between severity of CDB based on degree of sensory impairment and level of intellectual and communicative disability within the population. However, whether or not the child with CDB was able to make use of residual senses to access a linguistic culture (spoken or signed) correlated significantly with both cognitive and communicative ability. In addition, the two groups had inverse correlations between number of systems used for communication and communicative ability. The actual systems used for communication may be useful for categorizing people with CDB into severity subgroups for scientific study and for intervention planning. In addition, the acquisition of a tactile language for the subgroup of people with CDB who do not utilize a visual or auditory linguistic culture should be given special attention in research and practice.