The increasing linguistic complexity of 60 children aged 4 to 10 years whose mother tongue is French is studied for the first time in relation to the procedures involving reformulation that simplify, or render more complex, "source" sentences from a story that they have to retell. The syntactic opposition between simple and complex statements is reviewed from the perspective of a continuum in which both "complexification" and simplification are necessarily relative and dependent on a great many factors. The study shows, however, that the various procedures involved in the increasing complexity of a "source" utterance at the moment of its reformulation correspond to paraphrastic reformulations that are encountered in the following order: incomplete defining descriptive paraphrases, then complete ones; semantic paraphrases; formal paraphrases; transformations followed by restructurings and, finally, functional paraphrases.