Theory and empirical evidence suggest that self-esteem and the quality of social relationships are mutually related across long time spans, however, relatively less is known about this association in daily life. Experience sampling data of 232 Dutch Master’s students (Mage = 24.6, SDage = 2.7) was collected across 4 measurement waves including 14 days with 4 daily assessments in each wave. Dynamic Structural Equation Modeling was applied to study the within-day associations between morning/evening self-esteem and social interactions. First, we linked morning and evening self-esteem to the aggregated quality of social interactions during the day. Results showed that quality of social interactions during the day was associated with evening- but not morning self-esteem. Second, we linked anticipation of social interactions to morning and evening self-esteem. Positive anticipation of social interactions was positively associated with morning- but not evening self-esteem. Third, we investigated whether trait self-esteem moderated the within-day associations, but found no support for this hypothesis. Our results provide a better understanding of the daily short-term dynamics of self-esteem and social interactions in daily life – as they suggest that not only our actual social experiences, but also our anticipation of social interactions matter for daily self-esteem dynamics