Over the past 10 years the application of Ground Penetrating Radar (GPR) to pavement layer characterization has undergone significant developments. Current GPR technology is applied using non-contact equipment operating at normal driving speeds for data collection, and automated data processing software. Applications include determination of pavement layer thickness, identifying changes in pavement structure, and detection of pavement deterioration. The paper provides an overview of these applications, including: a synopsis of related research studies and results, expected levels of accuracy, requirements for ground truth, and availability of equipment and software. The paper also presents project case studies illustrating the key features of each current GPR application. Finally, the paper provides an update on current and in-progress specifications and standards for the application of GPR to pavement characterization.