This study investigated potential differences between expert and lay knowledge of factors influencing witness suggestibility. Expert psychologists (N ¼ 58), jurors (N ¼ 157), and jury-eligible undergraduates (N ¼ 220) estimated the effects of misleading information on witness accuracy for three age groups in various conditions. Respondents possessed similar knowledge of age-related trends in suggestibility, the positive effects of a pre-misinformation warning, and the negative influence of longer delays between the event/misinformation and event/final memory test. Compared to experts, laypeople underestimated the size of suggestibility differences between age groups and lacked knowledge about how event detail centrality, witness participation, and source prestige can increase witness suggestibility. Laypeople rated themselves as being largely unfamiliar with witness suggestibility research and thought that expert testimony would be beneficial. These data shed light on the potential helpfulness of expert testimony in cases involving witness suggestibility.