Implementation of evidence-based interventions (EBIs) in under-resourced schools serving ethnic and racial minority youth is challenged by intervention, individuals', and setting characteristics. Engaging community members in equitable partnership improves implementation outcomes and provides resources (e.g., workforce capacity, funding), but can be time intensive. Rapid and rigorous approaches for improving the implementation of EBIs in under-resourced schools is necessary to address youth mental health needs. In this paper, we describe a 6-week internship program for high school students (n = 8) that used community-based participatory research (CBPR) and user-centered design (UCD) principles to adapt a cognitive behavioral skills curriculum. We assessed the process by categorizing barriers discussed and addressed using the Consolidated Framework for Implementation Research, and qualitatively exploring youth perceptions of the adapted curriculum. Barriers included intervention complexity, intervention design, communication, and resource availability. Adaptations focused on design simplification (e.g., renaming the curriculum "TEB: Thoughts, Emotions, Behaviors") and dissemination strategies (e.g., creating social media content). Thematic analysis of intern interviews revealed the adapted curriculum as appropriate for students, helpful, and broadly applicable. Interns also expressed ownership over the curriculum and provided recommendations for future implementation. Overall, our study suggests the following: (1) CBPR and UCD can be integrated to adapt EBIs for racial and ethnic minority youth in school settings; (2) UCD principles can expedite the adaptation process; (3) design participation fosters a sense of ownership; (4) youth involvement in the design process can spur support from other stakeholder groups including policymakers; and (5) engaging youth as co-creators requires financial and human resources.