The objective of this article is to determine the factors that contribute to separatism in different countries of the world, as well as to find those means (forms and methods) of counteraction that would lead to an effective and preferably painless solution to such problems. The subject matter of the analysis in this article is social relations that are associated with counteracting the tendencies of separatism in the modern world, as well as the legal basis of such opposition. The following methods of scientific cognition were used while writing the article: systematic approach, logical, semantic, documentary, comparative and legal method. The urgent nature of the research problem has been noted, since the problem of the emergence of separatist movements is quite real for every country in the world. The definitions of the terms of “opposition to separatism” and “legal basis of opposition to separatism” have been offered. Suggestions in regard to overcome this negative phenomenon in a particular state have been provided. Factors that are the “catalysts” of separatism tendencies have been distinguished and stated in details. The historically recorded separatist movements and methods of overcoming them have been analyzed. The authors have made the conclusion about the individual causes and manifestations of separatism in a particular state. It has been proved that the existence of individual features associated with separatism, complicates to a large extent the creation of unique methods to combat this socio-political phenomenon. The authors have emphasized on the urgent need to improve the regulatory base of Ukraine on combating and preventing separatism, in particular, to develop and implement effective preventive, punitive and restorative mechanisms.