Adolescents' temperamental frustration is a developmental precursor of adult neuroticism and psychopathology. Because the mechanisms that underlie the prospective association between adolescents' high frustration and psychopathology (internalizing/externalizing) have not been studied extensively, we quantified three pathways: stress generation [mediation via selection/evocation of stressful life events (SLEs)], cross-sectional frustrationpsychopathology overlap ('carry-over'/common causes), and a direct (non-mediated) vulnerability effect of frustration, including moderation of SLE impact. Frustration and psychopathology were assessed at age 16 with the Early Adolescent Temperament Questionnaire and the Youth Self-Report. No gender differences in frustration were observed. At age 19, psychopathology was reassessed by using the Adult Self-Report, while occurrence of endogenous (self-generated) and exogenous (not self-generated) SLEs during the interval (ages 16-19) were ascertained with the Life Stress Interview, an investigator-based contextual-stressfulness rating procedure (N = 957). Half of the prospective effect of frustration on psychopathology was explained by baseline overlap, including effects of 'carry-over' and common causes, about 5% reflected stress generation (a 'vicious' cycle with the environment adolescents navigate and shape), and 45% reflected unmediated association: a direct vulnerability effect including stress sensitivity or moderation of SLE impact. After adjustment for their overlap, frustration predicted the development of externalizing but not internalizing symptoms.