A series of experiments on children and adults were conducted to define the features and workings of argumentative discourse. Oral and written arguments were analyzed for the complexity of the argument support structure and the presence of typological argumentation markers (certainty modals, value judgments, etc.). Subjects were asked to assess the argumentativity of texts that did or did not contain typical argumentation markers.At about age ten, children can produce and recognize a ‘minimal argumentative structure,’ in which the speaker takes a (...) stance and supports it with text that derives its argumentativity from the presence of this stance). However, full mastery of the negotiation process, that involves acknowledgment of the opponent's stance (generally through the use of counterarguments) is not present before the ages of 15 to 16. The minimal argumentative structure continues to develop with age and gain complexity. Certain situations are more conductive to the production of elaborate argumentative discourse, such as a genuinely controversial topic with an unfamiliar adult addressee whose stance is not known and whose reaction is thus unpredictable. Here speakers produce complex arguments while still leaving room for negotiation.Overall, certain argumentation markers can be identified in all argumentative text. these markers can be used to characterize stages of development of argumentative discourse. A number of issues remain unexplored, including: What other (implicit...) devices do speakers use to convince their audience? Why is the capacity to put argumentation in writing acquired at such a late stage of development? (shrink)