This contribution analyzes adaptation between child language and child-directed speech (CDS) during the development of grammaticalization in child language. The study compares developmental trajectories of three children (learning Dutch, Austrian German and French) with the trajectories of the CDS of their caretakers. It takes an exploratory approach to describing patterns of development and variability in specific aspects of language development, such as the relative frequency of one-, two/three- and more-word utterances, noun proportions in vocabulary, and determiner/filler use and omission. The analyses consist of descriptive techniques that can be used to visualize patterns of development, which are transferable to other contexts. The results point to real time, ongoing processes of accommodation that are part of an effective communicative flow.