Viruses cause diseases such as influenza, AIDS and SARS and thereby create a significant and ever expanding global threat to human health. The historical persistence, recent emergence and potential bio-terrorist use of viruses define both compelling and urgent reasons to better understand fundamentally the connection between viral growth and persistence. Many viruses exist in nature as genetically heterogeneous populations, but it is not known to what extent genetic variation impacts their response to host or other environmental factors. Current ‘gold standards' for the laboratory study of virus growth and persistence are limited. Synchronous ‘one-step' infections provide an average measure of virus production across a population of infected host cells, but they mask information about the distribution of behaviors. Serial-passage methods enable virus cultures to span many generations, but they are time- and labor-intensive to perform. We are pursuing two approaches to address these limitations. In the first, we combine flow cytometric measurements, sorting, and characterization of infected cells, with computational models of virus intracellular development to elucidate the kinetics of virus growth in single infected cells. The goal is to better understand quantitatively how genetic and environmental factors contribute to distributions in virus production from individual cells. In the second approach, we employ digital imaging and analysis of spreading virus infections to explore the population dynamics of viruses in three formats: (1) infections across micro-patterned cells, which enable real-time monitoring and parallel characterization of multiple virus populations, (2) focal infections on cells expressing intact interferon-signaling pathways, which will allow investigation into how communication between cells creates of a virus-resistant cell state, and (3) flow-enhanced growth and spread of viruses to advance a new measures of viral drug susceptibility. Recent highlights drawn from these studies will be presented. Long-term goals of this work are to advance viral diagnostics, vaccines and anti-viral strategies.