The article characterizes the works of L. Masenko, according to which the directions of research of the linguistic situation of Ukraine that are relevant today are determined, and the development of these directions in the works of other Ukrainian sociolinguists is traced. A number of the author’s publications are devoted to the analysis of the Soviet language policy aimed at limiting the functions of the Ukrainian language and artificially interfering with its structure in order to bring it closer to Russian. They present a brief period of Ukrainization in the 20th century, the policy of great terror that followed, the period of Khrushchev’s thaw, which was accompanied by a certain liberalization, and the subsequent period of intensified russification. In connection with the periodization of the Soviet language policy, the term linguocide was discussed. In several works of the scientist, the main parameters of the description of the modern language situation of Ukraine are defined. Such parameters include: the demographic power of languages, their communicative power in various spheres, in particular in the system of education, science, culture, mass media, and state administration. Equally important is attention to intergenerational features of communication, axiological parameters, etc. It was emphasized that the screening of the state of affairs in these areas should be regular, territorially oriented and carried out according to comparative methods. These features of the language situation are carefully covered in a collective monograph based on the results of an international scientific project under the leadership of Iu. Besters-Dilger (2006—2008) and in the materials of the next project under the leadership of M. Wingender (2016—2019), in which L. T. Masenko took part. The specified parameters are still relevant. In connection with the study of language behavior, the concept of language stability, which was proposed by O. Tkachenko at one time, was discussed. Attention is focused on topical issues of sociolinguistics, in particular, the study of the surzhyk phenomenon, which is ambiguously interpreted in the literature, with the involvement of a wide range of factual material. The importance of preparing materials for the formation of a scientifically based state language policy (a topic that L. T. Masenko is actively working on), in particular in the field of protecting the languages of indigenous peoples and the use of languages of national minorities, was also emphasized. Keywords: sociolinguistics, Ukrainian language, Surzhyk, language policy, linguicide, language stability