The concept of security-development nexus is central to the official discourse of both leading bilateral donors and international organizations assisting developing countries. On the one hand, the nexus is presented as a concept which has captured the essence of new challenges faced by developing countries in the modern context, and as a theoretical framework for evolving holistic, comprehensive strategies of development assistance – on the other. Paradoxically, the concept of the nexus itself, to a large extent, remains understudied. The present paper continues a series of studies on challenges and prospects of the nexus conceptual analysis. An underlying hypothesis is that a scientific definition of the nexus can be formulated by contextualizing this concept in a broader framework of security studies. The first section of the paper examines the current state of the nexus research area, outlines difficulties related to both a theoretical reflection on and a practical implementation of the nexus. The author comes to the conclusion that in order to understand the substance and the content of the nexus, one must turn to a study of its constitutive notions, namely, the notions of security and development. In this context, the second section outlines an original methodology for mapping of international security studies, based on the analysis of their ontological and epistemological foundations. Thereupon, the author distinguishes two fundamentally different approaches to conceptualization of the security problematique in international relations: traditional and postmodernist. The analysis of both the contemporary official discourse and theoretical plus empirical researches on the security-development nexus through this prism allows the author to formulate a general operational definition of the nexus, on the one hand, and to outline prospects for its instrumentalization –turning into an effective analytical tool for addressing international issues, on the other.