During young adulthood, several transitions in work and family lives occur, but knowledge of the work-family trajectories of the current generation of young adults, i.e. people born in the 1990s, is lacking. Moreover, little is known about whether the mental health status before the start of the working life may shape work-family trajectories. We used 18-year follow-up data from the TRAILS cohort study of individuals born between 1989 and 1991 (n = 992; 63.2% women). Internalising and externalising problems were measured with the Youth Self-Report at ages 11, 13 and 16 years. Monthly employment, education and parenthood states were recorded between 18 and 28 years. Applying sequence analysis, we identified six work-family trajectories in women and men. The first five trajectories were labelled: long education, continuous education and work, education and work to work, early work, and inactive. The main difference between trajectories of women and men was in the timing of parenthood, thus the remaining trajectory of women was labelled active with children, and the remaining trajectory of men active. Women who experienced externalising problems in adolescence were more likely to belong to the trajectory characterised by parenthood. Men who experienced internalising problems in adolescence were more likely to belong to the trajectory characterised by a long time spent in education. The TRAILS data allowed us to consider timing, duration and ordering of the work and family states in young adulthood, and to use multiple assessments of mental health in adolescence. Further research needs to examine the mechanisms through which early mental health affects later work and family outcomes.