This paper surveys the state of knowledge regarding development and humanitarian non-government organisation (NGO) responses to preventing and countering violent extremism (P/CVE). As well as delineating the nexus and shared objectives between P/CVE and development/humanitarian NGO frameworks, it outlines a reframing of the concept of VE into violent and hateful extremism (VHE), as a shift to a more nuanced understanding which addresses inherent complexities and entanglements more deeply. The Special Issue that this paper introduces is the product of a roundtable symposium held on this topic, with conceptual and empirical papers submitted by practitioners and academics who were invited to contribute due to their expertise in this area. The diversity of case studies, datasets, and author perspectives serves to advance knowledge on this topic and provide useful evidence and insights to inform policy and practice.