Despite practice guidelines for multiculturally competent care, including spiritual/religious diversity, most mental health graduate training programs do not formally address spiritual/religious competencies. Thus, we enhanced the Spiritual Competency Training in Mental Health (SCT-MH) course curriculum to train graduate students in foundational attitudes, knowledge, and skills for addressing clients’ spirituality and/or religion (S/R). The hybrid (online and in-person) SCT-MH course curriculum was integrated into existing required graduate clinical courses (replacing 15% of a course’s curriculum) and taught to 309 students by 20 instructors in 20 different graduate training programs across counseling, psychology, and social work disciplines. Using a multiple baseline waitlist control design in which students served as their own controls, students completed validated assessments at three timepoints evaluating their spiritual/religious competencies for understanding the intersection between S/R and mental health. We also collected qualitative data from the students to evaluate acceptability of the content and format of the training program. Students’ scores on all seven measures of spiritual/religious competencies had a statistically significant positive increase after engaging with the SCT-MH curriculum compared to the control period. At the end of the course, 97% of the students envisioned using spiritually integrated therapy techniques with their clients at least some of the time, 92% or more rated the materials as helpful and relevant, and 96% were satisfied with the training modules. Results demonstrate that dedicating a small (i.e., 6 hours of class time; 10 hours outside class time) but intentional amount of course time to teaching spiritual/religious competencies increases students’ attitudes, knowledge, and skills for attending to clients’ S/R in clinical practice. The SCT-MH hybrid course content is freely available to all graduate programs on our website. https://www.spiritualandreligiouscompetenciesproject.com/resources/sct-mh.