The article is devoted to the study of the characteristic features of the compositions of folk instrumental ensemble music of the 20th – first decades of the 21st century on the example of the Ukrainian Carpathians and Western Polissya regions. Research materials: the author's own records, archival and printed sources. Research methods: historicaldialectical (tracing evolutionary trends in folk ensemble cultures over the last century), analytical (analysis of the specifics of ensemble music), comparative-typological (comparison of different regional cultures of Western Ukrainian lands).As a result of the analysis of the material we can draw the following conclusions. The composition of traditional ensemble music depended on the established tradition of the ethnic environment, historical and cultural changes, specific performance situations and the individuality of professional musicians.Since the instrumental ensemble is a harmonious combination of individual performers, its texture specificity is extremely important for ensemble music. In Ukrainian folk instrumental music, the same instruments can perform different functions (melodic, accompanying, rhythmic), but the role differentiation between musicians is mostly preserved: on the one hand, soloist / leader, band leader, on the other – supporting and accompanying performers. Depending on the types and musical stylistics of the works, different types of polyphony are produced in ensemble music: monophony, heterophony (unison, bourdon, ornamental, ‘tape’), polyphony (tune-line, spontaneous contrast), homophony.Other characteristic parameters of ensemble music – musical system, tonality, melody, rhythm, tempo, dynamics, musical form – are typical not only for ensemble, but also for all Ukrainian folk instrumental music. It is in the ensemble rather than the solo context of the instrumental composition that it is best to consider each of them, so the analytical results will be more objective.In the 20th – first decades of the 21st centuries in the Carpathians and Western Polissia there were significant changes in the development of culture, its instrumental tradition, in particular, associated with the partial loss of specific genres and forms of music and their replacement by influx. Many changes took place in this period in the compositional features of folk ensemble music. As the number of bands increased, the musicians began to use new performing techniques. Influenced by the written tradition and other external factors, concert solo fragments appeared, homophony penetrated into the texture of the works, tonal music changed the old modal, in slowing down at the end of works with a corresponding decline in dynamics such as stage and concert, new episodes are introduced into traditional forms, etc. At the present stage, due to the sharp growth of communication environments (mainly due to the Internet space) assimilative cultural processes are deepening.