Stimulant use disorder is a growing contributor to drug poisoning and mortality in the U.S., disproportionately affecting Black communities because of stimulant-opioid polysubstance use and structural barriers to treatment. Contingency management (CM) is the most effective evidence-based treatment for stimulant use disorder but remains poorly implemented in some communities. The Cultural Adaptation of Contingency Management (Cul-CM) study is a multiphase, mixed-methods study designed to culturally adapt CM for Black adults with stimulant use disorder and evaluate preliminary outcomes. Guided by the PEN-3 cultural model and the ADAPT-ITT framework, the study includes a clinician survey and scoping review, followed by interviews and focus groups to identify culturally relevant factors affecting CM uptake and engagement. Findings and input from experts and community advisers will inform a culturally adapted CM protocol that maintains core treatment elements while modifying delivery. A three-arm pilot randomized controlled trial (n=60) will compare culturally adapted CM, standard CM and treatment as usual after a 1-week priming phase. Primary outcomes are stimulant abstinence and longest duration of continuous abstinence; secondary outcomes include acceptability, satisfaction, feasibility and retention. Yale University Institutional Review Board approval was obtained. Findings will be disseminated through publications, conferences and community-engaged channels.