The Chapter includes a series of reflections on security as a concept and phenomenon. The author emphasizes the idea that security, as a phenomenon, has now become a particularly complex concept, comprising a series of dimensions that require a broad theoretical approach, especially its objective and subjective perceptions. For the beginning, there are researched the concepts of “national security”, “state security” and „personal security”, based on scientific research and legislation of the Republic of Moldova (National Security Concept of the Republic of Moldova, National Security Strategy of the Republic of Moldova, Law on State Security), to determine their nature and relations. Subsequent, there are studied the essence and particularities of social security, being specified the constitutional regulation and guarantees of the right of the person to social security. Finally, is being studied criminological security as a new dimension of national security. This compartment includes an exposure of relevant ideas to argue the necessity of developing criminological security theory in the national scientific area. It emphasized the necessity of this theory not only for the development of criminological science, but also to enrich the practice of countering crime