We have developed an approach for multianalyte identification and quantitation using a single conventional radio frequency identification (RFID) tag that has been adapted for chemical and biological sensing. Unlike other approaches of using RFID sensors, where a special tag should be designed at a much higher cost, we utilize a conventional RFID tag and coat it with a sensitive coating. In this lecture, we will demonstrate the operation of these RFID sensors for selective detection of vapors and label-free biodetection.