Constraint programming (CP) is a declarative programming paradigm with many academic and industrial applications (from n-queens to planning, vehicle routing, and optimization, among other fields). Music composition has been one of these applications since the earliest works on automatic harmonization, and it remains a very special and challenging one due to its artistic (and highly subjective) nature. The early works on CP in music were limited to classical music composition, as the harmonization and counterpoint rules naturally translate into constraints. However, when contemporary composers began to be interested in constraints, CP became an essential tool in computer-assisted composition systems. As several contemporary musical pieces have now been composed "with constraints", it is reasonable to ask why CP applies so naturally to music, and what the particular features of musical problems are. This book presents information about recently developed musical CP systems from both the scientist's and composer's point-of-view. It will therefore be of interest to students and researchers of music technology, composers in the computer music scene, and music software companies-especially those trying to model high level musical behaviors (i.e., intelligent arpeggiation/arrangement on synthesizers, "Band in a Box" software, etc.), perform music data mining, and execute music taste engineering for online music delivery.