In the last years, some methods have been proposed for dealing with COTS component selection. In all of them, a key point is the comparison of the user requirements, which drive the selection process, with the capabilities of the evaluated COTS. Quality models are a means to obtain structured descriptions of COTS domains. Once built, COTS in a domain may be evaluated with respect to the quality entities included therein, quality requirements may be stated with respect to the quality model, and the classical factorrequirement negotiation process may be used for the selection of the most appropriate COTS.