“…Prior studies (Gruenewald, Chermak, & Freilich, 2013a; Gruenewald et al, 2013b; Spaaij, 2010) have distinguished between loners (e.g., The Unabomber), lone wolves (e.g., Fort Hood Shooter) and lone-wolf packs (e.g., San Bernardino shooters). Given the contentious nature of defining lone-wolf terrorism (see, e.g., Holt, Freilich, Chermak, Mills, & Silva, 2019; Spaaij, 2010), this study provides a conservative approach to the phenomenon that only considers an incident a lone-wolf attack if it was committed by one or two actors (i.e., dyads such as the San Bernardino perpetrators) with no direct ties to any formal organization. In other words, incidents committed by single actors with direct ties to a formal organization and incidents committed by three or more actors, regardless of group affiliation, were considered organized group attacks.…”