Wilms tumor is the most frequent renal malignancy in children. There are two main collaborative groups who have contributed to improve the quality of life of these patients by giving supporting evidence with their multicentric clinical trials [the National Wilms Tumor Study Group (NWTS), included in the Children’s Oncology Group (COG), in North America, and the Société International d’Oncologie Pédiatrique (SIOP)]. Their approach, although similar in certain points, differs in its philosophy. In COG, patients with renal tumors undergo upfront surgery and then, according to histology and stage, postoperative chemotherapy is administered. In SIOP, however, if a child between 6 months and 16 years old presents with a renal tumor, standard preoperative chemotherapy is started, followed by delayed surgery. Stage and histology classification comes afterwards, and they will guide postoperative treatment. Both SIOP and COG approaches state that lymph node sampling is mandatory during surgery and lacking to do so would preclude a worse prognosis. Standard surgical technique is an open radical nephroureterectomy, although there is some room for nephron sparing surgery and a minimally invasive approach in selected cases. Vascular extension with tumor thrombus can occur in Wilms tumor patients, and it should be removed carefully. Tumor rupture must be strongly avoided to prevent upstaging and consequent intensification of postoperative treatment, regardless of the approach. Further international collaborative research is needed to continue to improve the quality of life of Wilms tumor patients.