This report from the second Strategic Highway Research Program (SHRP 2), which is administered by the Transportation Research Board of the National Academies, evaluates existing IR and GPR technologies for their suitability in determining the density of hot-mix asphalt (HMA) pavements during placement and compaction. The technologies are reviewed in the context of four pilot projects conducted throughout the United States. Recommendations for integrating the use of these technologies into transportation agency specifications are offered as well. This project also produced a 30-minute training video (available on the TRB website) that gives an overview of equipment installation, data gathering, and data interpretation when using IR and GPR technologies.