Background Continuation of antidepressant medication (ADM) after remission is widely used to prevent depressive relapse/recurrence. Little is known about predictors of ADM use in terms of adherence, dosage, and successful tapering. The current study aimed to explore beliefs about the causes of depression and recovery (i.e., causal beliefs) and to examine whether they predict ADM use. Methods The data were drawn from a controlled trial and an extension of this trial with additional experience sampling. In total, 289 remitted patients with recurrent depression (ADM ≥ 6 months) were randomly assigned to Preventive Cognitive Therapy (PCT) with ADM tapering, PCT with maintenance ADM, or maintenance ADM alone. Adherence, ADM dosage, and causal beliefs regarding the first and last depressive episodes were explored via questionnaires. Results Most patients mentioned stressful life events as cause of depression, although more patients tended to endorse external causes for the first episode and internal causes for the last episode. ADM was most often mentioned as helpful during recovery from both episodes. Over half of all patients were adherent and under half of the patients in the tapering condition were able to complete the taper. Causal beliefs did not predict ADM use. Conclusions The results suggest that causal beliefs play little role in the use of maintenance ADM. More information is needed on factors contributing to successful tapering. The results must be interpreted with caution as this is not a naturalistic study and the results might be biased toward a more favorable view regarding ADM.