Evidence that early life exposure to acetaminophen causes neurodevelopmental injury in susceptible children has mounted for more than a decade. Evidence is diverse, including extensive work with laboratory animals, otherwise unexplained associations, factors associated with the metabolism of acetaminophen, and some limited studies in humans. Although evidence has reached an overwhelming level and has been reviewed in detail recently, some controversy remains. In this narrative review, some of those controversies are evaluated. First, the associations through time between acetaminophen use and the prevalence of neurodevelopmental disorders are considered. A systematic review reveals that the use of acetaminophen in the pediatric population was never tracked carefully, but historical events that affected use of the drug were documented and are sufficient to establish apparent correlations with changes in the prevalence of neurodevelopmental disorders. Second, problems with exclusive reliance on results from meta-analyses of large datasets and from studies involving small time frames of drug exposure are reviewed. Third, the potential bias in a study designed to separate the role of vaccines and acetaminophen in the induction of autism spectrum disorder (Autism 2008;12:293-307) is carefully evaluated. Finally, evidence demonstrating why some children are susceptible to acetaminophen-induced neurodevelopmental injury is examined. It is concluded that, at least among the factors considered, there is no valid rationale for controversy regarding the conclusion that early life exposure to acetaminophen causes neurodevelopmental injury in susceptible babies and small children.