Background: Several studies around the world report an increase in mental health problems among young people. Psychology is called upon to design ways to characterize these problems to make contextualized and effective interventions. The aim of this study was to analyze the factorial structure and reliability of the Social Determinants of Mental Health Questionnaire for Young Adults (SDMH), which was developed based on the Social Determinants of Health Model. Methods: This study included 1232 young Colombians aged 18 to 28 years (M = 20.88; SD = 3.52; 46.8% were women). The questionnaire design was rigorous and involved the participation of experts on the subject, peer review, and a pilot study. Statistical analyses included descriptive, reliability, exploratory, and confirmatory factor analyses. Results: The analyses indicate high reliability, and the confirmatory factor analyses reveal an adequate factorial structure. Conclusions: These findings suggest that the SDMH is a reliable and valid instrument for assessing the social determinants of mental health among young Colombians. Additional studies are needed to consolidate evidence of internal structure validity and provide more information on other sources of evidence regarding test validity.