Evidence on the association between early life mental health and alcohol use behaviours in adulthood is inconsistent. This thesis aims to summarise the available evidence in a systematic way, investigate the association from a developmental perspective and examine the co-development of alcohol use and stressful life events. In the systematic review, positive associations between externalising problems and alcohol outcomes were consistently reported, while associations between the internalising domain and alcohol outcomes varied across subtypes. Internalising problems tended to be negatively associated with alcohol consumption but positively with severe outcomes. Depression tended to be positively associated with alcohol outcomes, while no clear association was evident for anxiety. In two British birth cohorts, early life externalising and internalising problems were associated with problematic drinking in mid-adulthood, with externalising being a risk factor and internalising a protective factor. The strength of these associations did not differ by the developmental timing of externalising or internalising problems and cohort but was stronger in males. Mediation analysis indicated that in the UK context, the association between externalising problems and problematic drinking was not via educational attainment. In Michigan Longitudinal Study, three classes of individuals with heterogeneous dual trajectories of alcohol use and stressful life events over adolescence and young adulthood were identified. Two classes were characterised by consistently low levels of stressful life events with one class having a normative increase in alcohol use, while the other had a rapid escalation from ages 14 to 23. The third class had consistently high levels of alcohol use and stressful life events. Utilising prospective longitudinal data, the current thesis emphasises the interplay between externalising and internalising problems regarding their relationships with alcohol use, highlights potential sex differences in these and reveals the contextual role of stressful life events in the development of alcohol use
