The rapid growth of cultural diversity in the US population has urged training programs to prepare school psychologists and related school-based mental health practitioners to work with students from culturally diverse backgrounds. Accreditation bodies, such as the National Association of School Psychologists and the American Psychological Association, charge graduate programs with measuring growth in trainees in terms of competencies. As a result, multicultural competency is a domain of professionalism deserving of further study. The current study investigated the effects of a 10-week standalone graduate course on multicultural issues in school psychology, designed to increase self-assessed multicultural competencies in preservice school psychologists. The results indicated a significant increase in students' perceptions of multicultural competence across all 5 years of the investigation. In addition, using a two-way analysis of variance, cohort effects on growth over time suggested that the demographic composition of cohorts affected the growth in multicultural awareness, knowledge, and skills. Implications and recommendations for future school psychology research are discussed.