Amphibians are declining globally at unprecedented rates. To direct conservation efforts, global amphibian assessments are being conducted to characterize biodiversity and evolutionary relationships among species, as well as amphibian population and species' health. Modern molecular methods are facilitating such characterization, and we highlight techniques for rapidly increasing the availability of data for making taxonomic distinctions. When diversity is characterized, and populations and the species most vulnerable to declines or extinctions are identified, it is then critical to understand factors causing declines to develop mitigation strategies. We discuss molecular approaches and their applications for addressing some of the leading hypotheses for amphibian declines, including habitat loss, emerging infectious diseases, chemical contaminants, and global climate change.