To combat inequality at its root, in many countries family and parenting support programmes have been developed and implemented to assist families in creating stimulating home learning environments for their children. Practitioners working in these programmes are often confronted with highly complex, changing, and diverse work environments. However a clear description of the competencies these practitioners need to be successful does not currently exist. We conducted a qualitative case study and obtained in-depth knowledge about the necessary professional competencies from the perspective of financiers, providers, practitioners, and participants across three cases of family and parenting support programmes in Germany and the Netherlands. Results indicate that achieving family and parenting support programmes’ main objectives (high outreach and good implementation quality) requires practitioners to have the following professional competencies: high motivation, knowledge (didactical, pedagogical, tacit, content, and programme knowledge), and beliefs based on openness and respect towards diverse family lives, as well as adaptability, self-regulation, and cooperation and reflection skills. Further, the competency to establish trust and use trusting relationships with target groups facilitates the associations between the other competencies and objectives. We integrated our findings into a novel model of professional competencies for practitioners working in family and parenting support programmes, which can be used for further research and practice, as we also discuss in the article.