Designed for undergraduate courses on Expert Systems, PROLOG or introductory Artificial Intelligence, this informally-styled text assumes no background in PROLOG or Logic Programming, but combines an introduction to PROLOG with a mastery of its application to expert systems programming. Special features include: a clear ground tutorial introduction to PROLOG which goes beyond specific techniques and small programs to treat large, difficult Artificial Intelligence problems; a detailed discussion of how to program expert systems in PROLOG rather than a top-level, idea-oriented historical survey of what systems have already been built; four chapters on metalevel programming techniques; stress on the use of a pure subset of PROLOG coupled with logical analysis of the problem being solved; diagrams throughout the text to aid in the understanding of computational processes; and a large number of exercises, ranging from specific small programming problems to open-ended suggestions stimulate student creativity.