Study of the harmonic language of the late 19c based on songs by Hugo Wolf. The harmonic language of the late nineteenth-century is studied here as a development of common-practice tonality, taking as a model selected songs by Hugo Wolf. Late nineteenth-century romantic composers employed extended-tonallanguage in a variety of genres, and a special feature of such tonal exapansion was the use of extra musical elements. Hugo Wolfs output, encompassing over 160 miniature masterworks, displays all the necessary characteristics, and makes an ideal subject for studying extensions of tonality. The study is organised to focus on individual techniques of tonal expanison, then to explore the foundations of that technique, and finally, to illustrate the conclusions with particular Wolf songs. Necessarily, Wolf's relationship to Richard Wagner, and to Wagner's revolutionary musical language, forms a part of this study, and so too does the similarity of Wolf's music to that of his contemporaries.