It is well known that the compositions of Béla Bartόk are influenced by folk music. Until recently, however, musicologists in the West have treated this aspect of Bartόk's music superficially. By avoiding the folk music influence, their analyses are based on a partial knowledge only of Bartόk and consequently, the conclusions they make are severely limited. The purpose of this study is to delve deeply into the folk music influence on Bartόk's compositional style and to take full account of his ethnomusicological knowledge when analysing his music. In order to do this, I have limited my study to three of Bartόk's works, Sonata No.1 for Violin and Piano (1921), Sonata (1926) for piano and Contrasts for violin, clarinet and piano (1938). These compositions were chosen for three main reasons: first, there is only a relatively small amount written about them to date; second, they represent three different periods in Bartόk's creative life; third, they exhibit a rich variety of folk music sources, not only in terms of genre or nationality, but also in terms of the degree or level of influence. The study is in two parts, together with an introductory section. Part One is concerned with the direct influence of folk music on Bartόk's compositions and includes the imitation of folk genres, vocal and instrumental, and a variety of regions or nationalities. In the works under study, Hungarian folk song is the most prominent resource; this also reflects its foremost position in Bartόk's total output. Although of secondary importance, the instrumental repertoire and idiom has a significant role in all three finales from the Violin Sonata, Piano Sonata and Contrasts. A separate chapter is devoted to the verbunkos idiom in Contrasts, a type of Hungarian art music with roots in folk music. A chapter on the possible influence of the peasants 'sound-world' on Bartόk's style concludes Part One. This term describes the peculiar tonal qualities which Bartόk experienced in folk music. In addition, a section looks at 'mistakes' in the performance of folk music, and Bartόk's imitations of these in his compositions.

In Part Two, the indirect influence of folk music is discussed. This concerns general features of Bartόk's style - melody, harmony, tonality, rhythm and form – features that derive from his knowledge of folk music but which do not imitate specific genres or idioms. From intensive analysis of the works under study, it can be concluded that Bartόk's mature compositional language is pervaded with aspects of folk music. This mature language is well displayed in the Piano Sonata and Contrasts (although there are stylistic differences between these two), but in the Sonata No.1 for Violin and Piano (the earliest of the three), a dichotomy still exists between the elements of folk music and art music. In reaching this conclusion, it has been necessary to take into account non-folk influences in Bartόk's music. It has also been essential to examine other theoretical approaches, especially as they pertain to the works under study. Although some concepts and terminology have been adopted from other analysts, I have chosen to work mainly from the music itself rather than follow a particular method of interpretation.