The child welfare system is not a single entity. Many organizations in each community work together to strengthen families and keep children safe. Public agencies, such as departments of social services or child and family services, often contract and collaborate with private child welfare agencies and community-based organizations to provide services to families, such as in-home family preservation services, foster care, residential treatment, mental health care, substance use treatment, parenting skills classes, domestic violence services, employment assistance, and financial or housing assistance. Child welfare systems are complex, and their specific procedures vary widely by State. The purpose of this factsheet is to give a brief overview of the purposes and functions of child welfare from a national perspective.