IMPORTANCE The reported prevalence of peanut allergy among children in the United States has increased more than 3-fold in the last 20 years. Medical guidelines on the introduction of peanut as well as other allergenic foods have evolved with the emerging evidence that an early introduction to these foods is more beneficial than a delayed introduction. This review highlights the studies that have led to the evolving guidelines on peanut introduction in infants. OBSERVATIONS The prevalence of peanut allergy has increased despite the publication of guidelines from the American Academy of Pediatrics in 2000, which recommended a delayed introduction of peanut. Since the 2000 guidelines, studies have provided evidence to support an earlier rather than delayed introduction. As a result, the American Academy of Pediatrics updated their guidelines in 2008 to promote peanut introduction during infancy. Current evidence continues to support the benefits of an earlier rather than delayed introduction. CONCLUSIONS AND RELEVANCE Over the years, guidelines on the introduction of peanut have evolved, and recent literature suggests that an earlier rather than delayed introduction is beneficial to prevent peanut allergies in infants.