The ACT theory of skill acquisition and its PUPS successor provide production-system models of the acquisition of skills such as LISP programming, geometry theorm-proving, and solving of algebraic equations. Knowledge begins in declarative form and is used by analogical processes to solve specific problems. Domain specific productions are compiled from the traces of these problem solutions. The model-tracing methodology has been developed as a means of displaying this cognitive theory in intelligent tutoring. Implementation of the model-tracing methodology involves developing a student model, a pedagogical module, and an interface. issues associated with the development of each of these components are discussed. Work on tutoring and work on skill acquisition have proven to symbiotic; that is, each has furthered the other's development. Keywords: Analogy; Artificial Intelligence; Cognitive Science; Computer-Assisted Instruction.