In the aftermath of any terrorist attack, the prevailing concern is to prevent future attacks. The next step is finding the root cause in order to understand why it happened in the first place. This is precisely the case in the most recent terrorist attack in the United States -- at the Boston Marathon on April 15. A crucial part of this particular process is figuring out who radicalized Tamerlan Tsarnaev, how and when he was radicalized, and how to prevent future radicalization of other would-be terrorists. Obviously, we’ll never be able to prevent all radicalization, but understanding what happened to Tamerlan will help us understand and, hopefully, ward off other attacks.