Recent reports and papers on chimeric research highlight the promise of chimeric models of human neuropsychiatric disorders to ameliorate human suffering due to autism spectrum disorders, depression, and schizophrenia. These calls, however, typically do not acknowledge, much less address, criticisms of model creation and validation, or concerns about scientific conduct more generally. The ethical justification for the use of nonhuman animals in research depends on the production of benefits to humans based on such research. But the assessment and production of (...) benefits are highly uncertain and rife with both practical and conceptual challenges. This essay provides a general framework for classifying the benefits of biomedical research and then focuses on two factors that directly impact—and threaten—the production of knowledge in research that models neuropsychiatric disorders. (shrink)