Since 9/11, the number of terrorist attacks and the lethality of these attacks are increasing at alarming levels within the United States and abroad. Countering violent extremism depends on understanding the radicalization process that leads to terrorist acts, but radicalization within the United States is a complicated picture. This NIJ Journal article, Understanding Domestic Radicalization and Terrorism: A National Issue Within a Global Context, explains the objectives of NIJ’s Domestic Radicalization and Terrorism research portfolio and NIJ’s leading role in terrorism research at the national and international levels. It summarizes the findings of recent NIJ-sponsored research, such as a set of risk factors for radicalization, and highlights forthcoming research into topics such as community reporting and behavioral insights from the families of radicalized individuals. Finally, the article points to future research directions in areas such as disengagement and deradicalization for people convicted of terrorism-related offenses.