There is more to making one's self understood than knowing the meaning of words and the rules that govern how words (and the sounds that make them up) are put together. What is also required is the ability to use language effectively for the purposes of communication, a skill broadly referred to as ‘communicative competence’. Three forms of knowledge are relevant to this. The first includes the range of devices which enable speakers to communicate stretches of speech longer than a single sentence; this is referred to as discourse knowledge. The second is the shared knowledge that speakers and listeners have, which allows them to interpret aspects of meaning over and above the literal meaning of the words themselves; this is part of the area of linguistics known as pragmatics. The third subdivision of communicative competence forms the subject matter of another area of linguistics, that of sociolinguistics. Sociolinguistic knowledge covers the social conventions associated with the language one speaks, including knowing how to use language in different social situations, and how to adjust one's register depending on who one is communicating with.

Communicative competence develops gradually in children, and a rough idea of the importance of discourse and pragmatic knowledge in conversation can be gained from samples of speech from very young children. Hoff (2001) provided this example of a three-year-old who was asked to make up a story, and replied ‘A little duck went swimming. Then a crab came. A lobster came. And a popsicle was playing by itself.’