Despite a body of confessions research that is generally accepted in the scientific community, courts often exclude experts on the ground that such testimony would not assist the jury, which can use its common sense. To examine whether laypeople know the contents of expert testimony on confessions, we asked 151 lay participants to indicate their beliefs about 30 confession-related statements used in a recent survey of 87 confession experts (Kassin et al., American Psychologist, 2018, 73, 63-80). Participants agreed with experts on only 10 of the 30 propositions, suggesting that much of the psychology of confessions is not common knowledge and that expert testimony can assist the trier of fact.