This study sought to determine the effects of prior knowledge and other personal variables on the achievement of undergraduates in an economics course at the Open University of the Netherlands (OuN). A total of 100 law and 100 economics students enrolled in "Economics and Money" were tested on subject mastery at the end of the course. The study found little difference in the performance of the law and economics students on the test, contradicting the hypothesis that economics students should perform better than law students in such a course. Age, previous educational level, and employment experience also had little influence on performance. It is concluded that research in the field of "prior knowledge" will have to be reoriented and that an in-depth analysis and assessment of the virtual domain specific and subject oriented expertise of students is a more promising track. An appendix outlines the study variables. (Contains 10 references.) (MDM)