Abstract: A technique for tailoring electronic commerce user interfaces for a consumer dependent upon from which of multiple electronic commerce sites the consumer requests access to an electronic commerce service is provided. A first consumer request for an electronic commerce service is received by an electronic commerce service provider from a first site. This first request includes both a consumer identifier and a site identifier. The identity of a first entity on whose behalf the electronic commerce service is provided by the service provider is determined based upon the site identifier. A first unique user interface is then selected dependent upon the site from which the first request is received. A second consumer request is received for the service from a second site. This second request includes the same consumer identifier and a different site identifier. The identity of a second entity on whose behalf the service provider provides the electronic commerce service is determined based upon the site identifier.