Early childhood is an important developmental period, which lays the foundation for future learning, behaviour, physical and mental health and gene expression. The most vulnerable children in society are often referred to and receive services from the child welfare system because of a concern of abuse and neglect and/or a poor developmental trajectory. This paper presents an organizing framework for how the child welfare system, in concert with allied partners, can support interventions for young children and families by acknowledging its crucial role in improving their development and well-being. The framework is informed by research amassed from numerous disciplines, including child welfare, development, neuroscience, neurobiology and epigenetics. Although the notions of protection and well-being are central considerations in child welfare legislation in Ontario, Canada, the operationalization of wellbeing has proven challenging in child welfare practice, policy and research. The framework proposes ten key indicators and priorities for identifying and promoting optimal child development. Findings from the 2013 cycle of the Ontario Incidence Study of Reported Child Abuse and Neglect (OIS-2013), the only provincial source of aggregated child welfare investigation data, are presented to articulate the divide between the environmental context of a population of at-risk children and the conditions that both protect children and increase the likelihood that they will thrive in adulthood. This paper argues there are different points of entry and intervention across sectors and provides a foundation for further discussion on how to promote well-being for society's most vulnerable children.