Approximately 1 in 6 children in the US has a developmental delay, disorder, or disability (DD). Early identification of DDs can help families access services that empower children and families, and it can improve child outcomes. The "Learn the Signs. Act Early." (LTSAE) Program at the Centers for Disease Control and Prevention (CDC) encourages parents and providers to monitor every child's early development and act when there is a concern. In February 2022, LTSAE released revised materials that include updated developmental milestone checklists to better support ongoing conversations between families and professionals. This article describes the purpose of the checklists and how early childhood professionals can use these free resources to engage families in developmental monitoring.