Early childhood home visiting to improve health and development is commonly delivered by child health care (CHC) whereas home visitors from the social services are rare. We applied a constructivist grounded theory approach to explore the practice and contributions of parental advisors from the preventive social services in a home visiting collaboration with CHC in a socioeconomically disadvantaged area of Sweden. The analysis rendered a conceptual model of a situation-based practice, built on interactive encounters between parents and professionals. It includes strengthening of positive parenting, connecting parents to additional services, early detection of needs and provision of psychosocial support in accordance with each family’s specific situation. Rooted in the training and experience in social work, the practice can be seen as contributory to the delivery of complex support to families through home visiting and could provide input to efforts of improving training of home visitors in different contexts.