We examine whether parental externalizing behavior has an indirect effect on adolescent externalizing behavior via elevations in life events, and whether this indirect effect is further qualified by an interaction between life events and adolescents' GABRA2 genotype (rs279871). We use data from 2 samples: the Child Development Project (CDP; n = 324) and FinnTwin12 (n = 802). In CDP, repeated measures of life events, mother-reported adolescent externalizing, and teacher-reported adolescent externalizing were used. In FinnTwin12, life events and externalizing were assessed at age 14. Parental externalizing was indexed by measures of antisocial behavior and alcohol problems or alcohol dependence symptoms in both samples. In CDP, parental externalizing was associated with more life events, and the association between life events and subsequent adolescent externalizing varied as a function of GABRA2 genotype (p <= .05). The association between life events and subsequent adolescent externalizing was stronger for adolescents with 0 copies of the G minor allele compared to those with 1 or 2 copies of the minor allele. Parallel moderation trends were observed in FinnTwin12 (p <= .11). The discussion focuses on how the strength of intergenerational pathways for externalizing psychopathology may differ as a function of adolescent-level individual differences.