AbstractThere are two types of interlaboratory comparison studies: proficiency tests, which aim at monitoring the proficiency of laboratories, and test performance studies (TPS), which aim at evaluating the performance of (a) specific test(s) and whether it (they) is (are) fit for purpose. This booklet covers only TPS organisation. A TPS is usually organised to monitor the performance of a newly developed test to detect and/or identify pests or to compare the performance of different tests. The results of TPS also provide information on how (a) test(s) perform(s) in different laboratories. This allows a better estimation of the accuracy and reproducibility of tests. Organising a TPS is a complex process that requires considerable effort from the organisers in terms of time, expertise, and finances. Therefore, the selection of e.g. pests and of participants are important steps which are described in this chapter It also discusses the minimum criteria that the TPS organiser should meet.