Songsin N.Kunnapan K.Houngkom P.Hayiwani N.Sukam P.Kingkaew W.M.Siladlao S.Runnuch R.Wannapaschaiyong P.Mahidol University2025-10-172025-10-172025-10-01Journal of Public Health and Development Vol.23 No.3 (2025) , 191-20026730774https://repository.li.mahidol.ac.th/handle/123456789/112637Senior high school students aged 15–19 are adolescents in the transitional phase from childhood to independent adulthood, during which stress can quickly arise. Developing Mental Health Literacy (MHL) can play a crucial role in preventing severe mental illnesses. This study aimed to explore the MHL and mental well-being of senior high school students in Samut Songkhram Province, Thailand. This descriptive-analytical cross-sectional study was conducted on 510 senior high school students in Samut Songkhram, Thailand, using stratified random sampling. Data were collected using the MHL and mental well-being questionnaire. The Pearson correlation coefficient and linear regression were used for analysis at a significance level of 0.05. This study included 510 senior high school students, the majority of whom were female (57.8%), aged 16 years (30.6%), and in Grade 11 (37.6%). Most students were enrolled in the Science and Mathematics program (57.5%). Regarding academic performance, most of them had grades of 3.01 or higher (53.5%). Most students’ families had incomes between 10,001 and 30,000 THB (49.6%). MHL was at a moderate level, while mental well-being levels were low. A positive relationship was observed between overall MHL scores and mental well-being scores (r = 0.103, p = 0.034). After adjusting for the study program, the overall MHL score was found to be significantly associated with mental well-being scores (Beta = 0.118). However, the overall MHL score showed a significant negative association with mental well-being scores (Beta =-0.137) when adjusted for the school-record program. The study revealed that senior high school students exhibited a moderate level of MHL and a low level of mental well-being. Therefore, extracurricular activities should be implemented to enhance MHL and improve the mental well-being of senior high school students in the future, alongside developing comprehensive strategies to address and prevent mental health issues faced by this group.MedicineSocial SciencesArticleSCOPUS10.55131/jphd/2025/2303152-s2.0-10501822592526511258