Disparities in mental health need and service use among racial and ethnic minoritized (REM) youth remain a pervasive public health concern in the United States. Cultural adaptations (CAs) have been put forth as a way to increase the cultural and contextual relevance of evidence-based psychological interventions (EBIs) to improve treatment outcomes among REM youth. Currently, no measure of CAs to EBIs for REM youth in the United States exists in the literature. Using a multistage method, this study sought to develop such a tool, the Cultural Adaptations Content Checklist (CACC). In a previous foundational study conducted via a systematic literature review, authors identified a comprehensive list of existing CAs. In the first two stages, we used a modified Delphi method as a part of which expert practice and research stakeholders (N = 17) provided feedback on CA types, definitions, and groupings via survey methodology. In the third stage, we conducted cognitive interviews with a subset of participants (n = 10) to assess participant comprehension of the CACC. The final CACC was developed and consists of 36 CA types organized into eight groups. Implications for use of the CACC in research and practice are presented. (PsycInfo Database Record (c) 2024 APA, all rights reserved).