Previous analysis of the interaction patterns among a Down Syndrome child and peers in a regular school identified two major problems: fewer acceptance by other children, and flaw mediation of interaction among children. The present research designed, implemented and evaluated an intervention program for this classroom, based on functional analysis procedures, so the teachers could solve these problems, dealing with the child challenging behaviors, mediating interaction and improving the inclusion process in their class. The intervention was based on the co-operative consultancy and consisted on discussions with educators about problems found by using functional analysis and designed strategies to solve them, based on their behavioral function. At the end of the program, child and teacher achieved important behavioral changes. These may be concluded by the expressive decrease of both classes of problem behavior defined as intervention targets (Heteroagressive and Disruptive Behaviors), and also by the expressive growth of effective interventions according to behavior function.