The intention of this thesis is to discover, describe and evaluate the effect of the various sources in Ives's musical style. In the first part, one becomes broadly acquainted with the development of music in America from about 1620 onwards; for certain features and phenomena there have strdng`repercussions later, on Ives's personality and his compositional procedures. The thesis describes such genres as revival singing, minstrelsy, civil war songs, household music and ragtime whence the composer drew many sources. It charts the influences and tendencies to which he was subjected whilst growing up in a small American town, and observes the far-reaching effects that his father's experimental, pragmatic approach to music had on his impressionable son. The music, performance techniques and general attitudes that he encountered in his father's band and other musical gatherings, were to become important sources in the composer's style. The thesis evaluates the effect that attitudes fostered at Yale University in the 1890's had on Ives, and also the extent to which the musical idioms with which he came in contact there--theatre orchestras, art music as taught by his teacher Horatio Parker and church music--influenced him, resulting in his embarking on a career in business. The consequences of this, with respect to his musical style, are considered. The second part of the thesis is concerned with Ives's treatments, in his own compositions, of the pre-existent music described above. His use of sources is analysed from melodic, rhythmic, harmonic and formal standpoints, and then selected portions of his music are examined to show how consistent means of quotational development become apparent. His choice of texts is considered, and finally, some connections with other composers and authors are reviewed.