Background In recent decades, Family Quality of Life (FQOL) has emerged as a decisive construct, both to improve the living conditions of the families of people with disabilities and to assess the results on the services and supports that they receive. The aim of this research is to determine the perception of the families regarding their support needs, the quality of their partnerships with professionals, and their FQOL and then identify to what extent the supports of early childhood intervention centers have a positive impact on the families’ FQOL while exploring whether the family–professional partnership has become a fundamental intervening factor of FQOL. Method The participants were 202 families with children aged 0–6 with intellectual and developmental disabilities. We used the structural equation model to analyze the influence that the adequacy of the supports and the partnerships exerted on FQOL. Results The results indicate that the families have language and speech support needs for their children and information needs for themselves, and that they are mostly satisfied with their partnerships with the professionals and their FQOL. Our results also indicate that their degree of satisfaction with the support was a good predictor of FQOL and their ratings of partnership quality was a key factor interceding on this effect. Conclusions This study provides professionals and public institutions with guidance when designing plans to improve early childhood intervention centers so the quality of life of these families and the progress of children with disabilities living in Spain become progressively stronger.