Prof. David Cafiso, of the University of Virginia, is hereby recognized with the Silver Medal in Biology/Medicine for his outstanding research and service to the International EPR Community. Already as a graduate student, David developed novel spin label probes to measure membrane electrostatic potentials, which revealed new structural transitions in visual rhodopsin. As a faculty member, he applied EPR spectroscopy and site-directed spin labeling to study reversible membrane-protein electrostatic interactions that function in cell signaling systems and in membrane trafficking. There are processes that underlie human disease states such as cancer. More recently, his research efforts have relied on advance EPR spectroscopy to elucidate the molecular mechanisms by which neurotransmitter release is triggered by calcium at the synapse. He also has been applying EPR spectroscopy in-vivo and in-situ to examine structural transitions in bacterial transport systems. This work has demonstrated the importance of the native environment in membrane protein function and has provided new insight into transport mechanisms. The International EPR (ESR) Society is proud to honor Professor David Cafiso for his distinguished contributions to the society.