BackgroundThe Social Emotional Distress Scale-Secondary (SEDS-S) is a short measure designed for comprehensive school-based mental health screening, particularly for using very brief self-reported measures of well-being and distress. Whereas prior studies have shown validity and reliability evidence for the English version, there is a lack of literature about its psychometric properties for Spanish-speaking youths.ObjectiveTo examine the psychometric properties of the SEDS-S in a large sample of Spanish adolescents, providing evidence of its reliability, structure, convergent and discriminant validity, longitudinal and gender measurement invariance, and normative data.MethodsParticipants were 5550 adolescents aged 12–18 years old. Test–retest reliability was examined using Cronbach’s alpha and McDonald’s omega coefficients, and evidence for convergent and discriminant validity was measured using Pearson’s correlation. Confirmatory factor analysis (CFA) was used to examine structure validity, while multigroup and longitudinal measurement invariance analysis was conducted for longitudinal and gender latent structure stability.ResultsThe CFA supported a unidimensional latent structure, which was also observed to be invariant between gender groups and over time. The scale showed evidence of reliability, with coefficients above .85. In addition, the SEDS-S score was positively related to measures assessing distress and negatively related to measures assessing well-being, thereby providing convergent/discriminant validity of the total scores.ConclusionThis study provides the first evidence of the reliability and validity of the Spanish version of the SEDS-S for assessing emotional distress among adolescents, cross-sectionally and longitudinally. Furthermore, findings indicated that SEDS-S could be a suitable assessment tool for screening and program evaluation purposes at different contexts beyond the school setting.