Appendectomy group: Children allocated to appendectomy will undergo laparoscopic appendectomy within approximately 18 hours of randomization which is the current standard of care in all centers participating in this study. Participants will receive intravenous antibiotics from the time of randomization and be treated post-operatively with intravenous antibiotics according to a defined and standardized treatment regime based on consensus for this trial. Specifically, children with a macroscopically normal appendix or non-perforated acute appendicitis will receive no further antibiotics. Children with perforated appendicitis will continue to receive intravenous antibiotics for a minimum of 3 days, and may receive additional antibiotics per local practice. The type of antibiotics used in each center will be identical to those used in the non-operative treatment group. Following cessation of intravenous antibiotics, criteria for discharge home will be identical to those in the non-operative treatment group.