Dual-factor models of mental health are increasingly supported but little is known about longitudinal trends in dual-factor mental health. The current study used latent profile analysis (LPA) to empirically identify dual-factor mental health classes at each of Grades 9 through 12 and latent transition analysis (LTA) to examine stability of classes over four academic years. A sample of 875 adolescents from two cohorts reported on their social-emotional strengths and psychological distress. Cross-sectional LPAs for each grade year resulted in four mental health classes: complete mental health, moderately mentally healthy, symptomatic but content, and troubled. An LTA model indicated that the complete mental health class exhibited the most stability, followed by moderately mentally healthy and symptomatic but content classes. The troubled class exhibited the least stability. Less than 24% of participants remained in the same mental health class across all years. Findings support regular monitoring of students' dual-factor mental health to accurately inform mental health promotion, prevention, and intervention efforts. Keywords dual-factor mental health; stability; adolescent; latent profile analysis (LPA); latent transition analysis (LTA) Dual-factor models conceptualize mental health as the interaction between well-being and psychopathology and research supports the need to consider both in school-based mental health assessment, prevention, and intervention efforts (Greenspoon & Saklofske, 2001; Keyes, 2002; Suldo & Shaffer, 2008). The stability of psychopathology (e.g., Overbeek, Vollebergh, Meeus, Engels, & Luijpers, 2001) and well-being (e.g., Huebner, Funk, & Gilman, 2000) independently is well established; however, research examining the stability of dual-factor mental health is limited. Only three identified studies have examined the longitudinal stability of dual-factor mental health (Compton, 2016; Kelly, Hills, Heubner, & McQuillin, 2012; McMahan, 2012)-over five-month, seven-month, and one-year periods. It remains unknown to what degree adolescents' dual-factor mental health status remains stable or changes beyond one year during this dynamic period of psychosocial development.