"Promoting ecocitizen behaviours: Promoting ecocitizen behaviours will be considered in the light of the theory of commitment (Kiesler, 1971; Joule and Beauvois, 1998, 2002) which invites us to break with the presupposition that informing and convincing people is sufficient to lead them to adopt the new expected behaviours. Modifying ideas is indeed not enough to modify behaviours. However, researches in commitment procedures, and more particularly in the foot-in-the-door procedure, show that a person will more probably adopt a new expected behaviour when the presented arguments are preceded by obtaining a less costly act called preparatory act (cf. Joule and Beauvois, 1998, 2002). We will report an action research that includes commitment procedures involving four preparatory acts. Altener European Project: The action research has been carried out within the framework of the ALTENER European project ("energy force for children") in the Provence-Alpes-Côtes d'Azur region (France). An action research that includes commitment procedures involving four preparatory acts: It has been conducted in 11 primary schools and aimed at promoting ecocitizen behaviours from 9-10 year old pupils (for instance have a shower rather than a bath) and their parents (for instance replace a standard bulb with a low-consumption bulb). 700 families were concerned by the research, and 28 teachers were involved. During the school year, pupils were led to perform the following preparatory acts : 1/ to notice good and bad ecocitizen practices in their school, 2/ to notice good and bad ecocitizen in their own family 3/ to fill in a questionnaire on the family ecocitizen practices, with the help of their parents 4/ to stick a pro-environment sticker on the family refrigerator. At the end of the school year, children and parents were led, in writing, to commit themselves to modify some of their behaviours, by signing a « committing bulletin ». For a "committing communication": Results are very encouraging because almost all of children and families agreed to sign the committing bulletin. We will conclude in laying the basis of what we call the "committing communication" (cf. Joule, Py and Bernard, 2004). "