This article opens with a review of changes to the concept of professionalism since Hall's classic 1968 study. Research into the measurement of professionalism is then evaluated and test results are reported for Hall's measure of professionalism on samples of British accountants and research chemists. Good fit indices from confirmatory factor analysis were only obtained after heavily modifying the original scale to give a 15-item, 5-factor scale. Inter-factor correlations are low, casting doubt upon the measurement of a single underlying professionalism construct. Suggestions for reconceptualising professionalism in terms of process rather than structure are given.