In this policy brief, the authors examine and provide examples of the ways that public libraries have become invaluable partners in supporting family STEM learning. Although emerging research points to the strong influence of families on children's growth and development, a focus on joint parent and child STEM learning is still nascent. This brief examines how public libraries, with federal and state support, are creating STEM learning that brings together children and families across the K-12 years. It builds on the organization's previous policy report, "Leading Family Engagement in Early Learning: The Role of State Library Administrative Agencies" (ED585942).