What is a musical instrument? What are the musical instruments of the future? This anthology presents thirty papers selected from the fifteen year long history of the International Conference on New Interfaces for Musical Expression (NIME). NIME is a leading music technology conference, and an important venue for researchers and artists to present and discuss their explorations of musical instruments and technologies. Each of the papers is followed by commentaries written by the original authors and by leading experts. The volume covers important developments in the field, including the earliest reports of instruments like the reacTable, Overtone Violin, Pebblebox, and Plank. There are also numerous papers presenting new development platforms and technologies, as well as critical reflections, theoretical analyses and artistic experiences. The anthology is intended for newcomers who want to get an overview of recent advances in music technology. The historical traces, meta-discussions and reflections will also be of interest for longtime NIME participants. The book thus serves both as a survey of influential past work and as a starting point for new and exciting future developments.