In the relatively short time since 2006—when Theoretical Medicine and Bioethics published an issue on moral issues relevant to the use of nonhuman animals in research —significant changes have occurred for nonhuman animals in many quarters. Public sentiment, new policy initiatives, and scientific studies of nonhuman animals’ capacities have all influenced the ways in which nonhuman animals are perceived and treated in research. Today, a large body of information is available for use in decision making about the acceptability of using nonhuman animals in research. The articles in this issue assess how moral argument and empirical studies stand to guide animal research policies and practices in future years.Many in bioethics have come to regard issues of animal research as a subfield of research ethics, bringing it closer to human research ethics. Animal ethics, like public health ethics, has struggled for recognition in bioethics. As the contributions to this issue show, some in bioe.