Since the end of the Cold War, extremist Islamism has become a focal point of international security debate in academic and policy research. Much of the existing literature on Salafi-Jihadi Groups (SJGs), conventionally known as terrorist groups, examines the root causes of the emergence of these groups through the lens of three levels: individual, group, and international levels. Thus, individual extremists' desire for jihad, Islamism as a group ideology, and the sole great power's post-Cold War policies in the Middle East are considered as the three dominant root causes of the emergence of SJGs in the literature. If these three causal determinants are to hold, it begs the question of why SJGs do not emerge in every Muslim majority country where these elements persist. Why, for instance, did individual jihadis' personal desire for transnational jihad, Islamist ideology, and the US post-Cold War policies produce SJGs in Afghanistan and the post-Saddam Hussein Iraq but not in Saudi Arabia and Qatar? What factor, then, is responsible for this contradictory outcome in countries which in terms of the presence of the root cause of SJGs are similar? Taking these questions into account, I consider the degree of state fragility countries to be responsible for this contradictory outcome. This dissertation examines state fragility as a condition, but not a direct cause, of the rise of SJGs. It engages with a three-decade-long debate on the relationship between state fragility and terrorism and examines the empirical findings through the lens of international relations, international security, and development theories.