Peritraumatic distress and anxiety sensitivity are associated with complications in bereavement, including posttraumatic stress and prolonged grief reactions. The extent to which these factors interact to contribute to bereavement-related distress, however, remains unclear. This study investigates whether anxiety sensitivity moderates the association between peritraumatic reactions and posttraumatic stress and prolonged grief symptoms in a sample of young adults with a history of bereavement due to sudden, unexpected deaths. Participants were 606 undergraduate students recruited from two US universities. Results suggest that peritraumatic emotional and physical distress and anxiety sensitivity are all independently associated with both posttraumatic stress and prolonged grief reactions. Furthermore, the association between peritraumatic distress and prolonged grief, but not posttraumatic stress, is moderated by anxiety sensitivity. These findings point to several potentially important, clinically modifiable factors associated with a variety of bereavement-related mental health problems among a vulnerable group of grievers.