In recent years, there has been increased interest in trauma-related shame and guilt and their relationship to mental health. Little is known, however, about shame and guilt following mass traumas, such as terrorism. This study investigates the potential associations of trauma-related shame and guilt with posttraumatic stress (PTS) reactions after the terrorist attack of July 22, 2011 on Ut?ya Island in Norway. Interviews were conducted with 325 of the 490 survivors 4 to 5 months after the event. Multiple linear regression analyses were employed to investigate associations. In the month previous to the interview, 44.1% (n = 143) of participants had experienced at least some guilt for what happened during the attack, and 30.5% (n = 99) had experienced at least some shame. Shame and guilt were both uniquely associated with PTS reactions after adjusting for terror exposure, gender, and other potential confounders (frequent shame: B = 0.54, frequent guilt: B = 0.33). We concluded that trauma-related shame and guilt are related to mental health after mass trauma.