Some environmental influences, including intentional interventions, have shown persistent effects on psychological characteristics and other socially important outcomes years and even decades later. At the same time, it is common to find that the effects of life events or interventions diminish and even disappear completely, a phenomenon known as fadeout. We review the evidence for persistence and fadeout, drawing primarily on evidence from educational interventions. We conclude that 1) fadeout is widespread, and often co-exists with persistence; 2) fadeout is a substantive phenomenon, not merely a measurement artefact; and 3) persistence depends on the types of skills targeted, the institutional constraints and opportunities within the social context, and complementarities between interventions and subsequent environmental affordances. We discuss the implications of these conclusions for research and policy.