The purpose of this study was to investigate the validity of the Progr
ess Test that was specially designed for measuring the growth of knowl
edge and clinical reasoning skills in a problem-based medical curricul
um. Scores and subscores of students from the different categories of
the Progress Test were compared with their scores on a Clinical Reason
ing Tests. Both the Progress Test and the Clinical Reasoning Test reve
aled the same pattern of increasing scores over the years, and had a h
igh intercorrelation. Further analyses revealed that the clinical scie
nces subscore in the progress test explained the variations in the cli
nical reasoning test scores. The knowledge of the behavioural sciences
subscore made a small but independent contribution. The knowledge of
the biomedical sciences subscore did not have this independent effect.
These outcomes are discussed in this paper from the perspective of de
velopment of medical expertise research and theory. Some educational c
onsequences are also discussed.