PURPOSE: In 2019, 31% and 14% of young women and men worldwide - respectively - reported being not engaged in employment, education, or training (NEET), an important indicator of long-term socioeconomic vulnerability. This study examined the developmental pathways leading to NEET status in young adulthood by investigating the association between perinatal adversities and NEET status and the mediating role of adolescent externalizing behaviours. METHODS: Data were from the Québec Longitudinal Study of Child Development (QLSCD, n = 974). Latent class analysis identified four profiles of exposures to 30 perinatal adversities: Low adversity, the reference group; Fetal growth adversity, which includes participants experiencing adversity related to growth problems in utero and after birth; Delivery complications, which includes participants - or their mothers - who experience complications during birth; and Familial adversity, which includes participants who experienced adversity related to their family life. The associations between the perinatal profiles, NEET status - which was self-reported at age 21 years - and the putative mediating role of externalizing behavioural problems (self-reported at ages 15 and 17) were investigated using structural equation modeling. RESULTS: The risk of becoming NEET at age 21 was higher for children who experienced familial (OR = 3.19 [95% CI: 2.31-4.40], p < 0.001) and fetal growth (2.03 [1.11-3.71], p = 0.022) adversity. Externalizing behaviour problems mediated the association between familial adversity and NEET status (1.17 [1.05-1.30], p = 0.004). CONCLUSION: Interventions targeting perinatal risk factors and adolescent mental health can contribute to efforts to prevent NEET status in young adulthood.< Leer menos