In viral DNA packaging, the genome is compacted to high densities into a capsid by an ATP-hydrolyzing molecular motor. The study of viral packaging has advanced dramatically in recent years due to new biophysical methods, particularly single-molecule techniques. We review the insights afforded by these new tools into the initiation, translocation, and termination phases of the packaging process. Furthermore, by integrating single-molecule data with structural and biochemical information from related molecular motors, we develop and present a possible molecular model for ATP-dependent translocation by a viral packaging motor. © 2012 Elsevier B.V. All rights reserved.