Highly fluorescent silver nanoparticles (AgFNP) have been prepared by a facile photochemical method, yielding these materials in just a few minutes and with excellent long-term stability. The method makes use of photogenerated ketyl radicals that reduce Ag+ from silver trifluoroacetate in the presence of amines. While as functional materials these AgFNP can be described as of nanometer dimensions, we believe that the luminescence arises from particle-supported small metal clusters (predominantly Ag-2). The materials have been characterized by electron microscopy, fluorescence and absorption spectroscopy, fluorescence lifetime studies, and F-19 NMR spectroscopy. Exploratory work shows that the fluorescence from AgFNP can be efficiently quenched by paramagnetic quenchers, and these studies have been combined with electron paramagnetic resonance work.