The therapeutic alliance is among the factors associated with positive results in therapy and has been extensively studied in psychotherapy. However, it has received less attention in social work and family intervention. Considering that such intervention occurs mainly within the framework of institutions and public policies, this article aims to identify the contextual factors that facilitate or hinder the therapeutic alliance between family members and social workers within the child protection system, taking the Chilean protection system as a case study. This longitudinal study followed six professional–caregiver dyads for 11 months using various qualitative techniques. The facilitating factors included the strengths approach of the child protection agency, family participation, a friendly work environment, and external supervision from a senior social worker. Among the obstacles were the high numbers of cases per professional, the undervaluing of their work, excessive workloads, stigma towards the system, and the mandatory nature of services. Facilitating factors were linked to the initiatives of the protection agency, while limitations were related to the type of welfare system. Similar obstacles and facilitators were found at the international level regardless of the kind of child protection system. The study concludes with recommendations for decision‐makers and social worker educators.