Youth peer support workers (YPSWs) are young adults with lived experience of mental illness during childhood or adolescence who support young people receiving treatment in mental health services.... Show moreYouth peer support workers (YPSWs) are young adults with lived experience of mental illness during childhood or adolescence who support young people receiving treatment in mental health services. The contributions made by YPSWs are a promising development to facilitate consumer-centered and recovery-oriented care. Although the youth peer support workforce is expanding rapidly, structurally embedding YPSWs in practice is challenging. To overcome these challenges and thereby improve care for young people, insight into YPSW roles, barriers and facilitators for implementing and pursuing youth peer support (YPS) is a necessity. This systematic review examined the published literature to identify existing knowledge on YPSW roles in treatment settings, and the barriers and facilitators for implementing and pursuing YPS in practice. A total of 24 studies from a variety of youth serving contexts were included in this review. Thematic synthesis resulted in six YPSW roles and five themes with barriers and facilitators. The roles included the: engagement role, emotional support role, navigating and planning role, advocacy role, research role and the educational role. The themes explored the needs of YPSWs, experiences of YPSWs, relationships between service users and YPSWs, the collaboration process between YPSWs and non-peer staff, and organizational readiness. This review underlines that YPSWs likely are a valuable addition to numerous youth treatment contexts. Overall, the implementation of YPSWs is a multifaceted operation that requires careful planning. We recommend services to set clear and realistic expectations for YPSWs, to consider potential power imbalances between YPSWs and non-peer staff, to provide adequate resources to pursue YPS, and to approach the implementation of YPSWs with a growth mindset. Show less