BackgroundAustralia is an ethnically diverse nation with one of the largest refugee resettlement programs worldwide. Evidence suggests that although the risk of developing mental disorders in culturally linguistically diverse (CALD) adolescents may be elevated, professional help-seeking in CALD youth is low. This study sought to evaluate the face-to-face teen (tMHFA) and Youth Mental Health First Aid (YMHFA) training with a CALD focus, which aimed at improving mental health literacy (MHL) and skills in youth and adults assisting adolescents with mental health problems.MethodsAn uncontrolled pre-, post-, and follow-up design was used to measure improvement in MHL measures in year 10 students and adults.ResultsA total of 372 year 10 students from 2 high schools were trained. 308 responded to the pre-training questionnaire, 220 responded to the post-training questionnaire, and 256 completed the 3-month follow-up questionnaire. A total of 34 adults were trained, 32 responded to the pre-questionnaire and 31 responded to the post-training questionnaire and 20 completed the 3-month follow-up questionnaire. Following training, students were more likely to endorse ‘helpful’ adults as valid sources of help (p < 0.001) and these gains were maintained at follow-up (p < 0.01). Significantly higher levels of concordant (helpful) helping intentions were found after training (p < 0.01), and this was maintained at follow-up (p < 0.05). Significant lower levels of discordant (harmful) helping intentions were found after training (p < 0.001), and this was maintained at follow-up (p < 0.01). A significant improvement in adults’ knowledge of youth mental health problems and Youth Mental Health First Aid was noted from pre- to post-training (p < 0.01) and was maintained at follow-up (p < 0.01). Confidence when helping a young person with mental health problems increased significantly after training (p < 0.001) and this was maintained at follow-up (p < 0.05).ConclusionOur findings indicated the training led to an improvement in a number of measures of MHL and helpful intentions of both the adolescents and adults evaluated. These results indicate that CALD tMHFA and YMHFA are a recommended way of upskilling those trained and thereby leading to the improvement youth mental health in areas with high proportion of ethnically diverse groups.