The present work was conducted to identify the family understandings about the problem, to describe the relational dynamics of these families, to identify interventions that mobilized changes and to explore the transformations in the therapist. This is a qualitative research that used categorical analysis of cases. It was carried out with three military families who consulted for difficulties with their teenagers. The intervention was made from the systemic theoretical approach. The results showed that the symptoms of the adolescents were calls for change to their family systems. They were constructed in the interaction and all of them were related to unsolved family problem situations. The intervention was successful in changing the initial causal explanation: families arrived with their difficulties linear comprehension, with psychotherapy the family moved to a circular causality. If the first comprehension paralyzed them in pointing and blame, the second moved them to see that the problems were family affairs that needed to be solved together. The therapy also caused changes in the therapist. This research provides elements for intervention, but especially for the prevention. It leaves concerns that open thematic possibilities for further research. It has the merit to begin exploring the family dynamics of the military, a context with little attention from the systemic view.