Success in the domain of work is a salient developmental task of adulthood and a key indicator of adaptive function in the evaluation of health and psychopathology. Yet few studies have examined pathways to work competence, especially with strategies testing for cumulative cascade effects over time. Cascade models spanning 20 years were tested via structural equation modeling, linking work competence in early adulthood to antecedent competence in work and other domains of competence in childhood and emerging adulthood. Data were drawn from the Project Competence longitudinal study of 205 school children followed for 20 years. Relative fit of alternative models was evaluated by the Bayesian information criterion. As hypothesized, the effectiveness of adaptive behavior in earlier age-salient developmental task domains forecasted later work competence, which also showed strong concurrent links to competence in other domains. Results suggest there are numerous pathways by which success or failure in major developmental task domains in childhood and adolescence may influence adaptation in other domains and eventually work competence, both concurrently and cumulatively over time. Cascade effects highlight the potential significance for later work competence of childhood conduct (antisocial vs. rule-abiding behavior) and social competence with peers, in addition to the ongoing role that academic attainment may have for work success. Work competence also showed considerable stability over a 10-year period during early adulthood. Implications and applications for future research and intervention are discussed.