An advertising compliance monitoring system is provided that includes a backscatter tag affixed to a sign or marketing material or shopper ID card, the tag communicating with a backscatter reader. The tag includes a memory for storing tag data and a transmitter. The tag transmits tag data to a reader automatically on a periodic basis or when interrogated. The tag data includes an identification number used to identify the tag associated with a particular sign, price, marketing material or shopper. This data is processed by a computer to determine compliance with and/or exposure to a particular advertising program.