This paper describes DEGAS, a Diphone Editor and Generator for Animation and Speech. DEGAS is a simple to use, yet powerful computer program designed to give researchers the means to develop speech synthesis rulebases in a diphone framework. It is an open system, allowing an unlimited number of arbitrary symbols for phones, synthesizer parameters, and categories. An arbitrary number of rules can be formed by combining these symbols with boolean operators. Target values for every parameter are prescribed by the user to define postures for each phone. A transition profile, zero or more special event profiles, and duration rules are specified by the user to define the interpolation between the two sets of targets in a diphone pair. DEGAS provides immediate audio and visual feedback, as well as a means to create a complete diphone inventory.