Water-soluble fluorescent Ag nanoclusters consisting of several to ∼100 Ag atoms have received increasing attention in recent years due to their unique optical, electrical, chemical, and physical properties. Substantial effort has been made to develop different synthetic schemes to prepare stable, highly fluorescent water-soluble Ag nanoclusters and explore their potential applications in chemical- and bio- sensing, bio-imaging, and catalysis. The synthesis of sub-nanometer sized Ag nanoclusters in aqueous solutions, however, is challenging because Ag nanoclusters will tend to grow, forming more stable and larger Ag nanoparticles with reduced surface energy. In this chapter, recent advances in water-soluble fluorescent Ag nanoclusters, including a variety of preparative methodologies, structure and property characterizations, and potential applications in chemical- and bio- sensing, are reviewed.