This study assessed disclosures of lifetime sexual violence and social reactions using the Social Reactions Questionnaire Shortened (SRQ-S) in Iceland, with a focus on sex differences and relations to mental health. Because the Icelandic version of the SRQ-S has not been studied before, we also examined its factor structure and reliability. A phone survey was conducted with a nationally representative sample of Icelandic adults. Of 1766 participants, 563 (31.9%) had experienced sexual violence in their lifetime. Women were more likely than men to have experienced sexual violence and to have disclosed it to someone. About one-third of those victimized delayed their disclosure for over ten years. Younger survivors and those who knew their perpetrator were more likely to delay their disclosures, but no sex difference was observed in disclosure delay. The SRQ-S demonstrated reliability as measure of social reactions for men and women with two primary subscales, positive and negative. Participants reported significantly more positive reactions than negative reactions. Negative reactions were more robustly related to adverse mental health outcomes. The SRQ-S could be a valuable instrument for clinicians to identify individuals that have encountered negative reactions and to provide them with appropriate support in the Icelandic context.