Norway rats served for many decades as the main subject species in studies of animal behavior and its physiological and genetic substrates, and many tens of thousands of research papers were published concerning rats. Here, I first, discuss some of the reasons for the rise and fall of Norway rats as the focus of behavioral research with animals, then describe the origins of the domestic rat and natural history of its wild forebear before reviewing a few of the scores of areas of behavioral research in which Norway rats have served as subjects.