Abstract The Treatment Programme for Families with Children in Andalusia is fundamentally aimed at promoting the integral development of children and adolescents through the strengthening of parental competences and family preservation strategies. In the last 20 years, this programme has been applied to over 75 000 families, involving about 150 000 children and adolescents. The aim of this study was to analyse the effects of this family intervention programme on the quality of life and behaviour problems of the children. This quasi‐experimental and longitudinal study had two non‐randomized groups (intervention group and comparison group) and two evaluation measures (pre‐treatment and post‐treatment). The intervention group was constituted by 297 families (540 children) who had participated in the programme. The comparison group consisted of 95 families (138 children) at a similar risk level, although these families had not participated in the programme. The results showed a significant improvement in the quality of life of the children of the families that belonged to the intervention group, which was significantly greater than the evolution detected in the children of the families that belonged to the comparison group. The results of efficacy and efficiency of this type of practice constitute a quality criterion of evidence‐based programmes and a requirement to maintain public investment.