This thesis concerned the design and implementation of an extensible computer language for microcomputer users. The language was shown to provide a minimal set of features which can be extended toward particular applications. The interactive nature of the language was discussed, along with a description of each language feature.Also presented were implementation specifics involving the use of a technique called threaded code. Motivations for the use of extensible languages were discussed, along with suggestions for further extensions and applications.Ball State UniversityMuncie, IN 57406