This Article posits a substantial divide between scientific findings and the courtroom practice in cases where mistaken identification is alleged. After tracing the chronicity and significance of the phenomenon of mistaken identification, this Article reviews the science of perception and memory and the mixed and decidedly inadequate response of the courts to that body of knowledge and concludes with an assessment of the limits of cross-examination and the need for sophisticated advocacy in cases where eyewitness testimony is at the core of the prosecution theory of guilt. Put most simply, the efficacy of the “great engine” is overstated, and it is less likely to achieve its stated purpose than the little engine that could.