This Companion provides an up-to-date introduction to the life and music of Finland's greatest composer, Jean Sibelius (1865-1957). Divided into four sections, it explores Sibelius's early career, his major musical achievements, historical reception and influence, and the performance and interpretation of his work. Sibelius emerges as one of the most striking figures in twentieth-century music. The book will be of interest to performers and the general public as well as serious scholars.