Many individuals that engage with “terroristic content” do so in online settings. Most research on online exposure to dangerous materials focuses on the content and who is posting it, and thus there is a lack of understanding on what individual traits motivate individuals to engage with extreme online content. The Behavioral Inhibition System (BIS) controls motivations to withdraw from a stimulus and can coordinate anxiety responses to acts of terrorism (Carver, 2004). However, anxiety (and therefore the BIS) can also motivate individuals to engage further with terroristic material and/or groups via the “quest for significance” (Kruglanski et al., 2014). As such, individual differences in BIS functioning may play a role in governing the relationship between exposure to extremist content and motivations to engage in extremist behavior. Using an experimental survey design in which individuals are exposed to terroristic content in an online setting, this study explores the role of BIS sensitivity in the willingness to engage with terroristic content and individual differences in ensuing activism and radicalism intentions. In support of our hypotheses, BIS sensitivity predicted increased intentions towards radicalism and activism in support of a terrorist group after exposure to terroristic content online. These findings support the quest for significance model, which posits that existential anxiety can play a role in motivating individuals toward radicalization and violent extremism.