["Scandinavian Journal of Psychology, EarlyView. ", "\nABSTRACT\nMany trauma survivors mentally create alternative scenarios to the factual past (i.e., “what could have happened”), referred to as counterfactual thoughts (CFT). However, to date, research on the phenomenology of post‐trauma CFT is sparse. We aimed to systematically explore the characteristics and content of CFT reported by young survivors of a terrorist attack. Approximately 8.5 years after the terrorist attack on Utøya island in 2011, 220 survivors (52.3% females, M age = 27.5, SD = 3.65) described their most common CFT related to the attack. The characteristics (e.g., direction, structure, social focus, and timing) and content of the survivors' CFT were analyzed using thematic analysis. The participants provided rich and highly detailed descriptions of their CFT. Most antecedents (“if…”) were additive (action), self‐referent, related to events occurring during the attack (e.g., if they had helped others, been located differently, or tried to overpower the perpetrator). The majority of the consequents (“then…”) were upward and other‐referent, particularly related how someone who was killed could have survived. Of note, many described CFT involving self‐blame. Findings may have implications for clinicians in terms of understanding and alleviating psychological distress among survivors' post‐trauma. It is important that clinicians are aware of this phenomenon, so that they better can identify and help patients cope with their CFT.\n"]