It is vital to improve the mental health (MH) of young people in Hong Kong, where the suicide rate has nearly doubled among those aged 15-29 years since 2014. This multi-method evaluation aimed to assess Coolminds, which promoted MH literacy by engaging students, parents, and educators in secondary schools in Hong Kong. Students, parents, and teachers completed self-report measures before and after attending workshops aimed at raising MH literacy. Pre- and post-survey data were collected between November 2021 and August 2022. Qualitative data from participant feedback and a focus group interview with Coolminds staff were analyzed using descriptive content analysis. The final dataset included 2903 students, 395 parents, and 325 educators from 52 schools. Only 3 schools had engagement with all 3 key groups. Significant improvements in MH knowledge were observed after the Coolminds workshops for all 3 groups. Qualitative analysis identified a reactive approach to MH issues, and bureaucratic and logistical challenges as barriers to implementation. Findings support the effectiveness of the Coolminds curriculum in improving MH literacy for each group and the demand for MH promotions in school settings. The implementation challenges indicate the need for future initiatives to better align with local needs and practices.