Real-time, live-cell imaging techniques and single-particle tracking algorithms can be used to follow individual virus particles as they infect cells. This article describes the labeling of viruses and cellular structures with fluorescent probes to allow visualization in live cells. It also discusses how virus trajectories and virus-cell interactions can be imaged and analyzed. Methods used for time-lapse imaging are outlined, as are inhibitors and reagents used to study the role of the cellular machinery during viral infection. Algorithms for tracking virus particles and obtaining quantitative measurements of viral transport and virus-cell interactions are also included.