Objectives To test the diagnostic accuracy of the American Academy of Pediatrics (AAP) recommended food insecurity screener. Methods We conducted prospective diagnostic accuracy studies between July and November 2016, in Chicago, Illinois. We recruited convenience samples of adults from adult and pediatric emergency departments (12-month recall study: n|=|188; 30-day recall study: n|=|154). A self-administered survey included the 6-item Household Food Security Screen (gold standard), the validated 2-item Hunger Vital Sign (HVS; often, sometimes, never response categories), and the 2-item AAP tool (yes-or-no response categories). Results Food insecurity was prevalent (12-month recall group: 46%; 30-day group: 39%). Sensitivity of the AAP tool using 12-month and 30-day recall was, respectively, 76% (95% confidence interval [CI]|=|65%, 85%) and 72% (95% CI|=|57%, 84%). The HVS sensitivity was significantly higher than the AAP tool (12-month: 94% [95% CI|=|86%, 98%; P|=|.002]; 30-day: 92% [95% CI|=|79%, 98%; P|=|.02]). Conclusions The AAP tool missed nearly a quarter of food-insecure adults screened in the hospital; the HVS screening tool was more sensitive. Public health implications Health care systems adopting food insecurity screening should optimize ease of administration and sensitivity of the screening tool.