This chapter focuses on critical youth allyship as an approach and disposition held by adults engaged in authentic youth partnerships and how this orientation overlaps with social justice leadership approaches. A critical form of “allyship” is intimately connected to the multiplicity of social justice-oriented educational leadership approaches/models and key to the enactment of socially just leadership principles to enhance youth agency. Drawing on tenets common across social justice leadership orientations, research on enduring social justice issues experienced by Black male youth in educational environments, and adultism, this chapter problematizes youth-adult partnerships and allyship to advocate for the inherent imperative of critical youth allyship as a principle of social justice leadership. Using a YPAR project based on a youth-adult partnership with Black male youth addressing issues in their school and community illustrates how the adults’ mindsets and approaches evolved from partners to “allies” to “critical youth allies.”