Background and Objectives: Maladaptive emotion regulation strategies increase prolonged grief and depressive symptoms following bereavement. However, less is known about the role of adaptive emotion regulation strategies in adaptation to loss. Therefore, we examined the concurrent and longitudinal associations of three putative adaptive emotion regulation strategies (cognitive reappraisal, emotional expression, and mindfulness) with prolonged grief and depression symptoms. Design: A two-wave longitudinal survey. Methods: A sample of 397 bereaved Dutch adults (89% female, mean age 54 years) completed validated questionnaires to assess trait cognitive reappraisal, emotional expression, mindfulness and prolonged grief and depression symptoms at baseline (T1) and 344 participants completed symptom measures again six months later (T2). Results: Zero-order correlations demonstrated that mindfulness, cognitive reappraisal and emotional expression relate negatively to T1 and T2 prolonged grief and depression symptoms. In multiple regression analyses, controlling for relevant background variables, all emotion regulation strategies related negatively to T1 prolonged grief and depression symptoms. In multiple regression analyses, controlling for T1 symptoms and background variables, mindfulness predicted lower T2 depression symptoms. Conclusions: Adaptive emotion regulation strategies relate negatively to post-loss psychopathology symptoms, yet only mindfulness longitudinally predicts lower depression symptoms. Dispositional mindfulness may be a protective factor in psychological adaptation to bereavement.