There is a clear trend today towards non-invasive, dynamic, digital approaches to biomedical imaging, and a need for even higher resolution. Light is particularly well suited for such investigations, as its temporal, spatial and intensity range are unparalleled. A convergence of new capabilities from fields as diverse as electronics, optics, molecular biology, computer science and dye chemistry have transformed light microscopy from a traditional, static, 2D tool into a highly useful, dynamic, 3D research capability for biology and medicine. We believe that the understanding of certain fundamental biological functions by dynamic mapping of events in living systems is within reach, based on novel, interdisciplinary methods. For imaging molecular events with high resolution (live cells, in vitro), light microscopy has continued to improve in performance, and we survey here some of our recent progress. The same dynamic mapping can be extended to organs, whole animals and humans, by monitoring molecules labeled with the long-wavelength dyes that proved useful in microscopy. We report here results obtained by in vivo imaging of fluorescently labeled monoclonal antibodies, indicative of tumor location and evolution in nude mice.