We analysed both structural and functional aspects of sentences containing the four
adverbials “after”, “before”, “because”, and “if” in two dense corpora of parent-child
interactions from two British English-acquiring children (2;00–4;07). In comparing
mothers’ and children’s usage we separate out the effects of frequency, cognitive
complexity and pragmatics in explaining the course of acquisition of adverbial
sentences. We also compare these usage patterns to stimuli used in a range of
experimental studies and show how differences may account for some of the difficulties
that children have shown in experiments. In addition, we report descriptive data on
various aspects of adverbial sentences that have not yet been studied as a resource for
future investigations.