Depression is associated with the infrequent use of emotion regulation strategies that increase positive emotion and the frequent use of strategies that decrease positive emotion. However, prior research mostly relies on global, retrospective assessments that fail to capture dynamic relations between positive emotion and emotion regulation in ecologically valid settings. This study used an ecological momentary assessment (EMA) design to test whether depression is related to positive emotion regulation in daily life. We recruited 108 individuals to complete a 14-day EMA study, tracking strategy use and positive emotion over time. Higher momentary positive emotion was associated with greater subsequent use of positive rumination and less use of dampening. Elevated depressive symptoms, however, were associated with lower average use of positive rumination and higher average use of dampening. Depressive symptom levels did not modulate relations between positive emotion and emotion regulation strategy use. Less use of positive rumination and more use of dampening were related to lower levels of momentary positive emotion. Taken together, depression was associated with a pattern of strategy use that is associated with low positive emotion. Emotion regulation may help to explain positive emotion deficits in depression.