We compared what 160 U.S. judges, 57 law students, and 121 undergraduates know and believe about factors affecting the accuracy of eyewitness testimony. Judges were no more knowledgeable than were undergraduates, and both groups were less knowledgeable than were law students. For all 3 groups, increased knowledge of eyewitness factors was associated with beliefs that might reduce wrongful convictions. Participants in all 3 groups underestimated what potential jurors know about eyewitness testimony. The results suggest that increasing judges' knowledge of eyewitness testimony might help them to reduce wrongful convictions and to more accurately assess when eyewitness experts are needed. The results also suggest that law schools need to do a better job of educating law students about eyewitness testimony.