Methods and apparatus are disclosed for use in an RFID system comprising a plurality of RFID devices and at least one reader which communicates with one or more of the devices. In accordance with an aspect of the invention, identifiers transmitted by the RFID devices are received by the reader. The system determines a classification of at least one of the received identifiers, and implements a privacy policy for data associated with one or more of the received identifiers based at least in part on the determined classification. For example, the given RFID device may be configurable into at least a first state indicative of a first classification, such as a private classification, and a second state indicative of a second classification, such as a public classification. The reader may alter a type of query that it issues based at least in part on the determined classification. Alternatively or additionally, response by the given RFID device to a query received from the reader may be conditioned on the state of the RFID device. The reader may be configured, dynamically or otherwise, so as to issue queries causing such selective responses by the RFID devices.