The authors of this article seek to explain the dramatic rise of family member and youth influence in the field of children’s mental health over the last twenty-five years, using a classic framework addressing interpersonal influence. The article also describes the contribution of the Research and Training Center on Family Support and Children’s Mental Health to these changes, largely through its research on ways to strengthen family and youth participation, organizing, and effective advocacy. After reviewing how and why family and youth voice has increased so dramatically, the authors present examples of how increased family and youth voice has stimulated changes in practice, service infrastructure, and policy to achieve a more family-driven and youth-guided system of care. Four examples address the rise and impact of the authentic participation of family members and youth: family advocacy organizations, families as policymakers, family members’ influence on research, and families and the wraparound process.