In a brief psychological intervention developed with 20 aggressive boys, it was verified that the positive results need a further period of assistance. So, the author has chosen to work with play therapy, which objective would be to avoid that aggressiveness impaired intellectual performance and relationships. In this weekly play therapy, 13 boys aged between 8 to 12 years old were assisted, showing aggressiveness and bad intellectual performance, according to their teacher’s evaluation. After six months of intervention, an evaluation would show if the process should be continued or finished. Among the 13 boys, 8 obtained the aimed results. The benefits from the improvement of an aggressive child, whose behavior disturbs the school environment would be too extensive, since not only the child will benefit from it, but also the teacher, the family and later on, the society, that will not receive a potential transgressor