Constipation is a common pediatric problem. To assist health care professionals who care for children with constipation, the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) previously published a clinical guideline based on an integration of medical evidence with expert opinion. To evaluate studies published since then, the NASPGHAN Constipation Guideline Committee performed a comprehensive and systematic review of the medical literature since 1997, to identify, review and rate the quality of new evidence. Based on this review, the recommendations of the original clinical guideline were reaffirmed with several modified according to the new evidence. Below is a summary of the evidence reviewed for this update. The complete revised guideline is available online in its entirety.