The current research examined pre‐ and post survey data in two social justice trainings for adults who support youth, including staff and volunteers (Study 1, N = 44) at youth‐serving organizations and adults who mentor young Black men and boys (Study 2, N = 72). We investigate whether training participants’ self‐report scores of cultural competences (studies 1 and 2), self‐efficacy for race equity (Study 1) and racial self‐efficacy to support mentee (Study 2) changed between the beginning of the training and after the training. Furthermore, we examine whether the changes depend upon whether training participants share cultural background with the youth with whom they work. In Study 1, findings indicated that training participants reported significantly increased scores of cultural sensitivity and self‐efficacy for race equity. Individuals who were not first‐generation college students saw higher increases in sociopolitical awareness. In Study 2, participants reported significantly higher scores of cultural sensitivity and racial self‐efficacy to support their mentees. Furthermore, non‐Black and women participants showed greater increases in self‐efficacy than Black and male participants. These results fill a gap in the literature on the potential role of social justice trainings to increase cultural competencies among adults who work with diverse youth.