Americans tend to have strong psychological responses to terrorism (e.g., fear, anxiety) even though terrorism poses a very low objective risk of injury or death. Unfortunately, this is exactly what terrorists hope to cause. Terrorism is one of Americans’ top fears and more than 40% of Americans worry that they will be victims of terrorism (Gallup, 2017a). Additionally, since Muslims are commonly blamed for and associated with terrorism in the US, Islamophobia, or the unreasonable fear of Islam and Muslims, is a common response to terrorism. Terrorism-driven Islamophobia even manifests as hate speech against Muslims, hate crimes against Muslims, and targeted killings of Muslims. Such responses may relate to Americans’ risk perceptions for terrorism (RPT)—their subjective estimates of the likelihood that terrorism will cause injury or death. Little has been done to measure RPT. As such, this study tests a comprehensive measure of RPT while also assessing its relationship with Islamophobia. With data from a nationally representative sample of 512 US adults (collected via Qualtrics), structural equation modeling (SEM) was used to evaluate the psychometric validity of an RPT measure that included twelve items spanning the multiple facets of RPT based on previous risk perception research. Results indicated good fit to the data, supporting the measure’s validity. In addition, the results indicated that there was a significant, positive relationship between RPT and Islamophobia. It seems that Americans tend to overestimate RPT and that this phenomenon is positively associated with reported levels of Islamophobia. Future research should test for a causal relationship between RPT and Islamophobia, which may lead to opportunities to reduce Islamophobia by reducing RPT. Additional findings suggest that RPT is more strongly driven by perceptions of risk to individuals, rather than the US as a nation, and that tens of millions of Americans exhibit Islamophobia, aligning with previous research. Future directions, implications for risk communication strategies for terrorism, and the evolution of Americans’ perceptions of terrorism are discussed.