Object-oriented programming (OOP) is perhaps the most important new software engineering technology of the past decade and promises to be a key factor in much of the software of the 1990s. This edited collection of articles from Computer Music Journal provides a timely and convenient source of tutorials on OOP languages and software design techniques and surveys a wide range of existing applications of this technology to music and digital signal processing. Included are the popular OOP languages LISP, Smalltalk-80, and Objective-C, and applications such as music description and composition, real-time performance, and digital signal processing.Contents. Introduction. Tutorials and Technology. Machine Tongues VIII: The Design of a Smalltalk Music System, Glenn E. Krasner. Machine Tongues IX: Object-Oriented Programming, Henry Lieberman. Machine Tongues XI: Object-Oriented Software Design, Stephen Pope. Music Representation and Processing Tools. Flavors Band: A Language for Specifying Musical Style, Christopher Fry. FORMES: Composition and Scheduling of Processes, Xavier Roder and Pierre Cointe. An Introduction to the MODE System - A Musical Object Development Environment, Stephen Pope. An Overview of the Sound and Music Kits for the NeXT Computer, David Jaffe and Lee Boynton. Composition Systems. The Kyma/Platypus Computer Music Workstation, Carla Scaletti. An Introduction to the Creation Station, Henry Flurry. TTrees: A Tool for the Compositional Environment, Glendon Diener. Signal Processing Systems. Javelina: An Environment for Digital Signal Processor Software Development, Kurt Hebel. Virtual Digital Signal Processing in an ObjectOriented System, David Mellinger, Guy Garnett, and Bernard Mont-Reynaud.