Mental health in adolescence has been shown to have effects on several social outcomes in adulthood, such as education and workforce participation. Longitudinal studies on family formation and parental outcomes however, are few. The aim of this study was to examine the relationship between mental health in adolescence and parental outcomes, studying if, when and how many children individuals goes on to have. Methods: The data used was derived from a community based prospective longitudinal cohort, by a questionnaire concerning different aspects of mental health at age 16 and about parental outcomes at age 43. Mental health was measured through internalized mental health (worry, anxiety, depression) and behavioral problems (truancy, vandalism, being detained by the police, spending the night away, driving without a license). Logistic and linear regressions were used, as well as survival analysis. Confounders were controlled for in the regression analysis. Results: Men with optimal internalized mental health were more likely to become parents than men with non optimal internalized health, whereas no such connection was found for women. The only group where there was significant difference in age at first child found in the linear regressions were women with high levels of behavioral problems, they were younger than their low level counterparts. For men and internalized mental health however, signs of a non linear relationship was found. Women with high levels of behavioral problems were also more likely to have either one ore more than two children. Conclusion: Mental health at age 16 showed some relationship with the parenthood aspect of family formation, by the age of 43. These relationships were shown to vary between internal and external mental health measures as well as across gender.