Although courts and scholars have long recognized the weaknesses of eyewitness testimony, the legal system has yet to find a satisfactory mechanism for educating jurors—who are generally unaware of the complex psychological processes that affect eyewitness accuracy—about the inherent fallibility of such testimony. Many scholars argue that the best option is to allow an expert witness to testify to the factors that can affect an eyewitness’s ability to perceive and remember. Yet eyewitness expert testimony presents several practical and equitable concerns, and even in jurisdictions that allow eyewitness experts, trial courts have been far from consistent in their admission of such testimony. Cautionary jury instructions avoid many of the same pitfalls and, in fact, carry several inherent advantages. Many of the eyewitness instructions now given by judges, however, are ineffective: they contain ambiguous and confusing language, they are given at the end of trial as part of a long list of other legal instructions, and in many cases, they reinforce jurors’ erroneous assumptions about eyewitnesses. This Note argues that eyewitness instructions should be provided before the eyewitness testifies, thus alerting jurors in advance to the factors they should consider in evaluating the testimony. The Note also proposes a model instruction, which attempts to convey the relevant scientific and legal principles in a way that will be meaningful and understandable to lay jurors.