We conducted a longitudinal study to investigate how social support from the partner is related to mothers' affective well-being during their return to employment after maternity leave and whether expectations of that support have an additional impact. We differentiated four forms of support and their respective expectation discrepancies: emotional, instrumental, informational, and companionship. Further, we included the impact of meeting specific support expectations. A convenience sample of 288 women filled out questionnaires 2 weeks before reentry and then 1 month and 2 months afterward. Social support was associated with well-being, with emotional support having the strongest positive impact. Informational and instrumental support either were not related or were negatively related to affective well-being. Expectations had an additional influence but were inconsistently associated with affect. They became more important over time.