Background: Early difficult temperament and child mental health problems are consistently associated with impaired functioning in adulthood. We examined three potential pathways between difficult temperament in toddlerhood (age 2) and depressive symptoms (ages 21–23) and well-being (age 23): i) direct – early difficult temperament directly associates with these outcomes, ii) mediated – these direct effects are also mediated by a general psychopathology factor in late childhood/early adolescence (GPF; ages 7, 10,and 13), and iii) moderated-mediated – these mediated effects are also moderated by negative (age 42 months) and positive (age 33 months) parenting behaviors. Methods: The analytic sample included 1892 mother-child dyads (33.4% male children) from the Avon Longitudinal Study of Parents and Children (ALSPAC). Mothers reported on their child's difficult temperament, negative parenting, positive parenting, and child's mental health symptoms. In adulthood, participants reported their own depressive symptoms and well-being (i.e. mental well-being, life satisfaction, happiness). Results: First, early difficult temperament associated directly and positively with depressive symptoms, but negatively with well-being in adulthood. Second, the GPF in late childhood/early adolescence mediated these direct associations. Third, the mediated pathways were not moderated by negative or positive parenting. Limitations: i) low risk community sample, ii) early risks are based on maternal reports. Conclusions: Temperament is a risk factor for impaired psychosocial functioning in adulthood, manifested through increased susceptibility to psychopathology in childhood/adolescence. Although more research is needed to test their generalizability, these findings suggest that targeting early difficult temperament may alleviate the risk for later mental health difficulties and may increase general well-being.