Abstract To date, trust and reputation systems have often been evaluated using methods of their designers' own devising. Recently, we demonstrated that a number of noteworthy trust and reputation systems could be readily defeated, revealing limitations in their original evaluations. Efforts in the trust and reputation community to develop a testbed have yielded a successful competition platform, ART. This testbed, however, is less suited to general experimentation and evaluation of individual trust and reputation technologies. In this paper, we present TREET, an experimentation and evaluation testbed based directly on that used in our investigations into security vulnerabilities in trust and reputation systems for marketplaces. We demonstrate the advantages of TREET, towards the development of more thorough, objective evaluations of trust and reputation systems.