In recent years, over two hundred men and women born or raised in the West have participated in, or provided support for Islamic terrorist plots and attacks. Several studies have examined the demographics of homegrown Islamic terrorists: their socioeconomic status, education level, professional prospects, and possible mental illnesses. To date, no study has empirically examined the process through which these terrorists are radicalizing, which constitutes a substantial gap in the literature. This study seeks to address that gap through an empirical examination of 117 homegrown jihadist terrorists from the U.S. and U.K.