The Syrian uprising began as a secular, nationalist struggle in 2011 but gradually devolved into a vortex of sectarian warfare with more than 200,000 dead and another 10 million displaced. Amid the chaos, the radical Sunni Islamist groups Ahrar al-Sham, Jabhat al-Nusra, and the Islamic State became the most prominent in the conflict. This book explores why and how the groups emerged in Syria, rose to power, and proliferated to unprecedented levels by tracing the progression of the Syrian conflict through three cycles of contestation: protest, insurgency, and civil war. Combining elements from social movement, insurgency, and radicalization theories as well as civil war literature, this book dissects the radical Islamist ideology, the institutional legacies from prior struggles, and the role of external sponsors; and places each in the context of the Syrian conflict. History has proven that the radical Islamists fighting in Syria today are the next generation of leaders in the global jihad movement. Understanding their rise to power provides crucial insight to our future enemies. This book seeks to go beyond a recitation of facts and links multiple frameworks with the rise of the most powerful radical Islamist groups in the Syrian conflict.