A definitive study of Janácek's Sinfonietta, tracing its creation, reception, and rise to international prominence. This book provides a musical 'biography' of Leoš Janácek's (1854-1928) most famous orchestral piece - his Sinfonietta - by analysing its sources, composition, reception history, recordings and musical component parts. The most up-to-date research on the genesis and performance history of the work, it considers in detail Janácek's orchestral writing, the inspiration and genesis of the Sinfonietta, a documentation of all the surviving sources for the work, the work's performance history during Janácek's lifetime and following his death until the end of the Second World War, including press reviews and relevant correspondence. The book also examines the growth in the worldwide popularity of the Sinfonietta. This evolved from cautious and hostile critical responses to the premiere recording in 1946 to its gradual acceptance as one of the key works of the 1920s, largely thanks to the advocacy of conductors whose work is considered in detail, alongside other significant recordings. Questions of performance, rehearsal, interpretation and the musical text are considered in a wide-ranging interview with the conductor Jakub Hruša, and a concluding chapter provides a detailed commentary on the music itself. The book includes a valuable appendix describing the annotated scores used by conductors such as Otto Klemperer, František Neumann and Henry Wood, as well as a comprehensive discography.