PurposeAdolescents with psychiatric disorders are known to be more often not in education, employment, or training (NEET) in young adulthood than their peers. However, since most of the available evidence is based on cross-sectional measurement of NEET, there is less evidence on the processes underlying these differences in labor market disadvantage. We assessed these processes by examining transitions between NEET and non-NEET states across young adulthood and the differences in these transitions by adolescent psychiatric inpatient treatment. MethodsWe used longitudinal register data on all individuals born in Finland in 1980–1984 (N = 315,508) to identify psychiatric inpatient episodes between ages 10 and 19 and NEET between ages 20 and 34. We modeled the transitions between NEET and non-NEET states and the impact of psychiatric disorders on these transitions with multistate models. ResultsIndividuals who had psychiatric inpatient episodes in adolescence started their labor market careers as NEET twice as often as their peers. They were also more likely to transition into NEET states and less likely to transition out of NEET. In total, individuals with a history of psychiatric episodes spent from 1.8 to 6.9 more years as NEET between the ages 20 and 34 than their peers, depending on sex, baseline NEET, and diagnostic group. DiscussionAdolescents with severe psychiatric disorders are highly vulnerable in terms of labor market outcomes throughout their early adulthood. Supportive measures are required both at the start of employment trajectories and during later career stages.