Research has underlined the necessity to prepare pupils to cooperate in order to boost cooperative learning benefits. However, this kind of training may appear very demanding. The present study aims to demonstrate that a short preparation related to social support and targeted cooperative rules relevant for the task increases constructive interactions. Thirty-two pupils from grade 6 (11.8 years) were involved in dyadic cooperative controversy (Johnson and Johnson 2007) on argumentative texts for one session. All pupils were presented with three targeted rules for controversy. Half of the pupils had a short intervention related to the demonstration of social support, and the three targeted cooperative rules for controversy were explained and discussed (listening carefully while affirming understanding, criticizing ideas, but not people, and focusing on common goal). The pupils' interactions during cooperative controversy were videotaped and coded and the individual learning regarding the content of the studied texts was assessed. Results indicated that those pupils who had been prepared to cooperate displayed more support, asked more questions, and paid more attention to their partner. The overall quality of cooperation inside the dyad was also evaluated as more positive, though no difference in learning outcomes was observed. In summary, a short preparation for cooperation elicited more constructive interactions.