Previous studies suggest that cognitive control training (CCT) shows potential as a preventive intervention for depression. In this study, the first to examine long-term preventive effects of CCT, we examined effects on (a) task-specific cognitive transfer at 1-year follow-up, (b) recurrence of depression, and (c) functioning over the course of a year. Each of 92 remitted depressed patients were randomly assigned to a CCT condition or an active control condition (ACT). Effects of training were monitored using weekly assessments of emotion regulation, cognitive complaints, depressive symptoms, and resilience (brief weekly questionnaire). At 1-year follow-up, participants completed a structured clinical interview, cognitive transfer task, and questionnaires. We observed task-specific cognitive transfer ( p < .001, d = 1.23) and lower recurrence rates in the CCT condition ( p = .04; odds ratio = 0.38). However, no long-term beneficial effects of training were observed on the weekly ratings of functioning, and groups did not differ in performance on the self-report questionnaires at 1-year follow-up.