Nineteenth- and twentieth-century research with non-human animal models of concussive brain injury elucidated many critical facts about the character and location of typical damage. It was, however, often flawed. Setting aside the unavoidable delay in the progress of neurobiological knowledge, and the fragility of the assumption that rodent brains change as human brains do, avoidable errors seem to have delayed the conduct of experiments plausibly designed to mimic human concussion. Investigators have largely failed to replicate typical human head motion, the dispersion of forces by the skull, and (due to anesthesia) the acute motor and behavioral effects of an abrupt external force. In addition, almost no reports attempt to explain gross differences in outcome after the same injury, overlooking biological individuality in the quest for a parsimonious account. By far the most disappointing failing, however, is the remarkable paucity of long-term outcomes research. This has perhaps seriously delayed progress in understanding late effects.