Despite current prioritization of the inclusion of young people's voices in the design and delivery of services for youth and young adults, few up-to-date tools or frameworks have emerged to assist service-providing programs, agencies, or systems in evaluating their efforts. Further, though stakeholders may be on board with the general purpose and principles for including youth and young adult voice in organizations and systems, they may lack awareness of the policies and practices that need to be developed to ensure the consistent and meaningful engagement of youth as participants in decision-making processes. This review synthesizes the state-of-the-science regarding how to support meaningful participation of young people in organizations and systems, closing with a review of existing assessment tools and the introduction of two new measures for agency- and system-level self-assessment of the conditions that support the meaningful inclusion of youth voice.