In a dual-factor model of mental health (cf. Greenspoon & Saklofske, 2001), assessments of positive indicators of wellness (i.e., subjective well-being—SWB) are coupled with traditional negative indicators of illness (i.e., psychopathology) to comprehensively measure mental health. The current study examined the existence and utility of a dual-factor model in early adolescence. The SWB, psychopathology, academic functioning, social adjustment, and physical health of a general sample of 349 middle school students was assessed via self-report scales, school records, and teacher reports regarding students' externalizing psychopathology. The existence of a dual-factor model was supported through the identification of four mental health groups: 57% of the sample had complete mental health, 13% was vulnerable, 13% was symptomatic but content, and 17% was troubled. The means of the four groups differed significantly in terms of academic outcomes, physical health, and social functioning. Results support the importance of high SWB to optimal functioning during adolescence, as students with complete mental health (i.e., high SWB, low psychopathology) had better reading skills, school attendance, academic self-perceptions, academic-related goals, social support from classmates and parents, self-perceived physical health, and fewer social problems than their vulnerable peers also without clinical levels of mental illness but with low SWB. Among students with clinical levels of psychopathology, students with high SWB (symptomatic but content youth) perceived better social functioning and physical health.