Scholars and policymakers often make noticeable distinctions between acts of terrorism and mass shooting incidents. In order to assess if these distinctions are generally accurate, we identity four key criteria from standard international and domestic definitions of terrorism. The criteria include: a political, religious, ideological, or social motivation; intent to reach a larger audience; the motivation not involving personal monetary gain; and the manifestation of an ‘enemy/other’. We analyze 105 mass shooting events in the United States from 1982 through October 2018 to assess whether they meet these criteria and find that 41 (39%) incidents meet all four criteria and another 45 (43%) incidents meet three of the criteria to be classified as acts of terrorism. Thus, we contend that mass shooting incidents fit the standard definitions of terrorism to a greater degree than is often reported by government officials, academics, and media outlets. We contend that researchers must be more persistent in investigating the motivations behind mass shooting events in order to accurately label and counter them.