Negative expectations concerning social interactions contribute to feelings of loneliness. Since loneliness is one of the most pronounced challenges for bereaved individuals, we investigated grief-specific social expectations and its association with loneliness and grief severity. Initially, we developed an Inventory of Social Expectations in Bereavement (ISEB). Its factorial and psychometric validity was then tested in a bereaved sample (N = 344; 28.3 ± 11.1 years; 74.4% female). A two-factor solution for the scale fit the data best (factor 1: "relationship to others," factor 2: "relationship to the deceased") and demonstrated good psychometric validity. Higher ISEB-levels were associated with higher levels in grief severity and loneliness. The results suggest that individual social expectations affect the experience of loneliness after the loss of a significant other. The ISEB assesses these expectations time-efficiently and provides a basis for therapeutic interventions. Expressing expectations as probabilistic beliefs about the future renders them amenable for corrective experiences in clinical practice.