Virtually all aspects of RNA metabolism involve RNA helicases, enzymes that remodel RNA and RNA-protein complexes in an ATP-dependent fashion. How RNA helicases catalyze such reactions is a key question in RNA metabolism, with implications ranging from understanding the regulation of gene expression to delineating the cellular response to viral infections. In this seminar, I will present recent results that illuminate how different RNA helicases couple ATP binding and hydrolysis to RNA duplex unwinding. Our data reveal a remarkable diversity of unwinding mechanisms among these enzymes.