In 2006, a consensus concerning functional gastrointestinal intestinal disorders in infants and toddlers was described. At that time, little evidence regarding epidemiology, pathophysiology, diagnostic workup, treatment strategies, and follow-up was available. Consequently, the criteria for the clinical entities were more experience based than evidence based. In the past decade, new in-sights have been gained about the different functional gastrointestinal intestinal disorders in these age groups. Based on those, further revisions have been made to the criteria. The description of infant colic has been expanded to include criteria for the general pediatrician and specific criteria for researchers. The greatest change was the addition of a paragraph regarding the neurobiology of pain in infants and toddlers, including the understanding of the neurodevelopment of nociception and of the wide array of factors that can impact the pain experience.