This report is part of the 2018 State-of-the-Science Series from the Research and Training Center for Pathways to Positive Futures at Portland State University. The author discusses the current move toward including young people’s voices in the design and delivery of services for youth and young adults and the need for updated tools and frameworks to assist service-providing programs, agencies, and systems in evaluating their efforts in this area. Despite agreeing with the general purpose and principles for youth and young adult voice inclusion in organizations and systems, stakeholders may lack awareness of the policies and practices required to ensure the consistent and meaningful engagement of youth as participants in decision-making processes. The author reviews the state-of-the-science on how to support meaningful participation of young people in organizations and systems, the existing assessment tools, and introduce two new measures for agency- and system-level self-assessment of the conditions that support the meaningful inclusion of youth voice. (author abstract modified)