This study examined the experiences of loss among bereaved adults, and the association between loss-related factors and mental health outcomes. Participants were 2023 bereaved adults from the United Kingdom and Ireland who completed measures of their bereavement experiences and symptoms of depression, anxiety, and somatization. The highest proportion of participants and those at greatest risk of meeting criteria for all disorders were those with less time since loss, who were in contact with the deceased every day or not at all in the year prior to their death, experienced sudden unnatural death, and those who lost a partner/spouse or a child. Age of the deceased was negatively correlated with meeting criteria for depression, anxiety, and somatization. Overall, depression, anxiety, and somatization were common in the bereaved population. Identifying key loss-related variables-such as time since bereavement and nature of death-will help target those needing urgent psychological support.