Book excerpt: Mass Shootings and Civilian Armament provides the first comprehensive multi-methodological analysis of the relationship between mass shootings and firearm purchases (as proxied by background checks) in the US on national level data from 1999-2020. Since 1994, the number of civilian-owned firearms in the US has doubled to around 398 million while the population only grew by 70 million. On average, mass shootings have occurred once every two weeks over the last decade which is a major factor behind why social scientists have started to ask whether mass shootings play a causative role in civilian decisions to purchase guns. Utilizing a multi-methodological approach featuring quantitative, comparative/configurational, and qualitative methods, this book puts forward a theoretical framework and argues that mass shootings do increase civilian armament, but that this repetitious effect is historically contingent, asymmetric, and non-linear. Particular types of mass shootings are hypothesized to have driven and continue to bring about increased levels of civilian firearm purchases through different pathways and combinations of variables – those that feature high fatality counts; arise in areas of cultural importance, are ideologically motivated. First, inquiry into background check data (1999-2020) and data on 213 mass shootings and attempted mass shootings is carried out to find out which shootings (as well as controls) are significantly correlated with background check increases. Second, the findings are utilized in a theoretically driven comparative configurational assessment to test if the noted theoretical pathways are associated with the outcome of increased post-shooting armament. Third, the empirical analyses are complimented by three case studies – the 2011 Gabrielle Giffords shooting (illustrative of the high fatality pathway), the 2012 Colorado movie theater shooting (illustrative of the cultural pathway), and the 2015 Charleston Church shooting (illustrative of the ideologically driven pathway). Interdisciplinary in nature, Mass Shootings and Civilian Armament will not only be of great interest to scholars of Criminology, but will also speak to sociologists, economists, public policy scholars, political scientists, historians, as well as cultural studies and American studies scholars.