"Smithtown" is an intelligent computer program designed to enhance an individual's scientific inquiry skills as well as to provide an environment for learning principles of basic microeconomics. It was hypothesized that intelligent computer instruction on applying effective interrogative skills (e.g., changing one variable at a time while holding all else constant) would ultimately lead to the acquisition of specific subject matter. This paper presents an evaluation of "Smithtown" in two studies of individual differences in learning. Experiment 1, an exploratory study with 30 undergraduates, demonstrated that "Smithtown" fared very well when compared to traditional instruction on economics and indicated the performance indicators that separated better from worse learners in this microworld environment. Experiment 2 extended these findings using 530 Air Force recruits interacting with "Smithtown." Performance indicators relating to hypothesis generation and testing were the most predictive of successful learning in "Smithtown," accounting for more of the variance in the learning criterion than did a measure of general intelligence. Differentiating behaviors between more and less successful subjects agree with specific behaviors relating to individual differences found in general studies on problem solving and concept formation. Findings can suggest modifications to enhance intelligent tutoring systems. Five tables and 11 figures contain study data. An appendix lists the original 30 learning indicators used. (Author/SLD)