GLISP is a high-level LISP-based language which is compiled into LISP using a knowledge base of object descriptions. Lisp objects and objects in AI representation languages are treated uniformly; this makes program code independent of the data representation used, and permits changes of representation without changing code. GLISP’s object description language provides a powerful abstract datatype facility which allows the structures and properties of objects to be dcscribcd. Reference to objects is permitted in an English-like syntax, including definite reference relative to the current context of the computation. Object-centered programming is supported. When interfaced to a hierarchical representation language, GLISP can perform inheritance at compile time, resulting in substantial performance improvements. In addition, a LISP structure can be specified as the way of implementing a class of objects in the representation language, making simple objects efficient in both time and storage.