IntroductionRumination has mostly been studied in relation to depression, however, it may also occur in response to positive emotions (i.e., positive rumination), and therefore may be a protective factor related to the maintenance of positive mood.ObjectivesWe hypothesized that daily positive and negative affect would be associated with daily positive and negative rumination even after controlling for trait‐level rumination.MethodsWe carried out a diary study with university students (n=178), where participants had to answer short surveys online about their daily affect and daily rumination every evening for ten days. We analyzed our data with multilevel regression in R.ResultsDaily positive and negative affect were significantly associated with daily negative and positive rumination, while trait‐level rumination scores were not. Daily and trait‐level rumination were moderately correlated (r=0.333‐0.440).ConclusionsOur findings highlight that daily rumination plays a more significant role in daily emotional experiences than trait rumination across positive and negative valence domains. Daily negative affect appears to be more closely related to higher daily negative rumination than the lack of daily positive rumination, which could be relevant for intervention strategies.