In 1940, 100 years after the proclamation of British Sovereignty of New Zealand, a young composer, Douglas Lilburn, returned to his native New Zealand from advanced musical studies in London. His music, drawn from the twentieth-century nationalism of Sibelius and Vaughan Williams and looking towards the New Zealand environment, marked the beginnings of a specifically New Zealand tradition of composition. This study is concerned with the life of Douglas Lilburn – the first New Zealand composer - and his compositions written for traditional (non-electronic) media. It is not only the study of one man and his music, but also a study of a composer who, due to circumstances of time and place, had to pioneer a tradition of serious professional composition in a young, isolated country. This study is in three parts. The first comprises a documentation of the life of Lilburn, tracing his history from birth (1915) to retirement (1980). The circumstances surrounding the composition of many of his works are examined, as is the role he played in furthering opportunities for composition in New Zealand. Part II examines the work of Lilburn through a representative sample of thirty of his compositions written for traditional media. The analysis is concentrated upon the works written between the years of 1940 and 1965 with a view to defining the style of the music, and charting the progression of that style through the given period. Part III summarises the preceding two parts as well as offering an examination of the quality of 'New Zealandness' in his music. Lilburn's work is set briefly in perspective against the work of other New Zealand composers. The conclusion is reached that Douglas Lilburn was not only the composer to pioneer the tradition of New Zealand composition, but also, between the years 1940 and 1965, the central figure in its development.