We conducted a quasi-experiment to compare the characteristics of experts’ and novices’ test-driven development processes. Our novices were 11 computers science students who par- ticipated in an Extreme Programming lab course, the expert group consisted of 7 professionals who had industrial experience in test-driven development. The novices as well as two of the experts worked in a laboratory environment whereas the remaining five experts worked in their office. The experts complied more to the rules of test-driven development and had shorter test-cycles than the novices. The tests written by the experts were of higher quality in terms of statement and block coverage as well. All reported results are statistically significant on the 5 percent level. We conclude that the results of studies which evaluate performance of test-driven development using subjects inexperienced in TDD are not easily generalisable.