More than a decade of sustained declines in child protective services maltreatment reports, substantiated reports, and foster care placements started reversing course in 2012. Meanwhile, the opioid epidemic has continued to intensify, and substance use is impairing a growing number of parents and placing their children at risk of poor parental care. It is well-established that parental substance use challenges children, families, and the child welfare systems charged with ensuring child safety, achieving permanency, and strengthening families to successfully care for their children. But what is less understood is how drug use, especially opioids and polysubstance use, is associated with the increase in child welfare cases. U.S. Department of Health and Human Services (HHS) researchers conducted a mixed methods study to explore the relationship between the two trends. This brief explores their results.