This article describes the development of a measure of interventionists' competence in implementing culturally responsive multitiered systems of support (MTSS) practices. We ran an exploratory factor analysis (EFA) on a 30-question survey that measured the multicultural competence of 651 school counselors and psychologists in MTSS implementation. The EFA indicated a five-factor structure of the Interventionist MTSS Multicultural Competence Scale (IMMCS): (a) Cultural Knowledge, (b) Cultural Awareness, (c) Cultural Skills, (d) Cultural Appreciation, and (e) Respect for Cultural Differences.