The Five Factor Model (FFM or Big 5) traits of extraversion, agreeableness, conscientiousness, neuroticism and openness, have all been associated with alcohol use. However, the vast majority of these studies have used cross-sectional designs, limiting the ability to evaluate the temporal relationships between childhood personality traits in adult alcohol use patterns. In the current prospective community cohort study (N = 329), we examine the predictive value of FFM traits measured in childhood and adolescence (starting at 6-9 years of age
well before the typical age at which adolescents begin drinking) for alcohol use in adulthood (27-30 years of age), spanning an average of 22 years. Personality was assessed with the Hierarchical Personality Inventory for Children (HiPIC) across 5 consecutive waves utilizing multiple informants (child, mother, father, and teachers). Alcohol use was measured by the self-report Quantity-Frequency Variability Index (QFV). A series of regression analyses indicates that during adolescence, high levels of extraversion and low levels of agreeableness are both (independently) associated with heavier drinking. These associations are robust and consistent from the first adolescent wave (age 12-15 years) to the last adolescent wave. Notably, informant-dependent measures from early childhood waves (ages 6-9) were not significant predictors, highlighting the importance of considering developmental context and informant variability. By leveraging a longitudinal design with temporally separated measures of personality and alcohol use, this study minimizes concerns about reverse causality. The results highlight the long-term relevance of adolescent personality traits in understanding adult drinking behavior and suggest that targeted prevention strategies focusing on highly extraverted and low-agreeable adolescents may help reduce harmful drinking patterns later in life.