This paper collection entitled “Protecting the Homeland from International and Domestic Terrorism Threats: Current Multi-Disciplinary Perspectives on Root Causes, the Role of Ideology, and Programs for Counter-radicalization and Disengagement”, seeks to add insights without needlessly repeating what has been heard and read elsewhere. What separates this paper collection from the many others on this topic is the multiplicity of perspectives represented, both domestic and international, that span the spectrum of social sciences. To do this, over forty authors were asked to provide perspectives on various aspects of terrorism: root causes, dynamics of Violent Non-State Actors (VNSAs), the role of ideology in terrorism, and potential solutions for counter-radicalization, deradicalization, and disengagement from terrorism.