Resumen: The aim of this preliminary research is to explore the effect of a brief protocol based on acceptance and commitment therapy (ACT) applied to five adolescents (15-17 years old) with conduct disorder and impulsivity, who had received treatment for the last few years without positive results. Problematic behaviors were aggressive, impulsive, and oppositional reactions at school, home, and neighborhood (e.g., drugs or alcohol consumption, legal violations, oppositionist and defiant reactions, etc.). A brief ACT protocol was designed to functionally suit the presence of impulsivity and the absence of self-control repertory of these adolescents as well as the resistance to psychological treatment. The brief protocol was focused on four aspects: (a) to set a context between the therapist and the adolescents to promote the sense of personal responsibility, (b) to confront the adolescents with the effect of their behavior regulation (pros and cons) and the experience of creative hopelessness, (c) to clarify personally important valued directions, and (d) to promote defusion skills so that the adolescents could take charge of their private experiences and choose actions according to their values. Four 90-min, individual sessions were implemented over two weeks. Participants and teachersâ reports obtained before, during, and after the treatment implementation showed a high positive change. In addition, 1-year follow-up information showed an important change in a wide range of areas such as family, social relationships, school achievement, and occupational status. These results suggest that brief ACT protocols can have a great impact on at-risk population. Limitations were discussed. Idioma: Inglés Año: 2014 Publicado en: Revista internacional de psicología y terapia psicológica = International journal of psychology and psychological therapy 14, 3 (2014), 307-332 ISSN: 1577-7057 Originalmente disponible en: Texto completo de la revista