For two decades, militant jihadism has been one of the world's most pressing security crises. In civil wars and insurgencies across the Muslim world, certain Islamist groups have taken advantage of the anarchy to establish political control over a broad range of territories and communities. In effect, they have built radical new jihadist proto-states. Why have some ideologically-inspired Islamists been able to build state-like polities out of civil war stalemate, while many other armed groups have failed to gain similar traction? What makes jihadists win? In Jihad & Co., Aisha Ahmad argues that there are concrete economic reasons behind Islamist success. By tracking the economic activities of jihadist groups in Afghanistan, Somalia, Pakistan, Mali, and Iraq, she uncovers an unlikely actor in bringing Islamist groups to power: the local business community.