Inclusion Criteria:

* Patients with the first occurrence of any tumor of the kidney identified on CT scan or MRI are eligible for this study; histologic diagnosis is not required prior to enrollment but is required for all patients once on study
* Eligible tumors include (but are not limited to):

* Nephroblastic tumors

* Nephroblastoma (Wilms' tumor) (favorable histology, anaplasia \[diffuse, focal\])
* Nephrogenic rests and nephroblastomatosis
* Cystic nephroma and cystic partially differentiated nephroblastoma
* Metanephric tumors (metanephric adenoma, metanephric adenofibroma, metanephric stromal tumor)
* Mesoblastic nephroma (cellular, classic, mixed)
* Clear cell sarcoma
* Rhabdoid tumor (any malignant rhabdoid tumor occurring outside the central nervous system \[CNS\])
* Renal epithelioid tumors of childhood (papillary renal cell carcinoma, medullary renal cell carcinoma, renal tumors associated with Xp11.2 translocations, oncocytic renal neoplasms after neuroblastoma)
* Angiolipoma
* Ossifying renal tumor of infancy
* Patients with the first occurrence of the following tumors are also eligible:

* Extrarenal nephroblastoma or extrarenal neprogenic rests
* Malignant rhabdoid tumor occurring anywhere outside the central nervous system
* Required specimens, reports, forms, and copies of imaging studies must be available or will become available for submission and the institution must intend on submitting them as described in the protocol procedures
* For ALL patients, (with exception of bilateral, bilaterally predisposed, multicentric, or unilateral tumor in solitary kidney planning to enroll without biopsy\*\*\*), the following submissions are required:

* A complete set of recut hematoxylin and eosin (H \& E) slides (including from sampled lymph nodes, if patient had upfront nephrectomy)

* \* Tissue must be from diagnosis, prior to any renal tumor directed chemotherapy or radiation (only exception is for presumed favorable histology Wilms tumor \[FHWT\] patients discovered to have diffuse anaplastic Wilms tumor \[DAWT\] at delayed nephrectomy and plan to enroll at delayed nephrectomy)
* Representative formalin-fixed paraffin-embedded tissue block or if a block is unavailable, 10 unstained slides from a representative block of tumor, if available.

* Tissue must be from diagnosis, prior to any renal tumor directed chemotherapy or radiation (only exception is for presumed FHWT patients discovered to have DAWT at delayed nephrectomy and plan to enroll at delayed nephrectomy)
* Institutional pathology report, Specimen Transmittal Form, and Pre-Treatment Pathology Checklist
* Copies of images and institutional reports of CT and/or MRI abdomen and pelvis, and Pre Treatment Imaging Checklist
* Copies of images and institutional report of chest CT for all malignant tumors
* Institutional surgical report(s) and Pre-Treatment Surgical Checklist
* CRFs: Staging Checklist and Metastatic Disease Form (if metastatic disease is noted on imaging)

* Patients with bilateral, bilaterally predisposed, multicentric, or unilateral tumor in solitary kidney planning to enroll without biopsy via imaging only - these patients will not have central review or have a risk assignment issued, but may contribute to specimen banking for future research. However, if biopsy is done, tissue must be submitted as for other renal tumors, and initial risk assignment will require pathology and surgical rapid central reviews. The Specimen Transmittal Form and Pre Treatment Pathology Checklist are also needed.
* Please note: if the above required items are not received within 120 days of study enrollment, the patient will be considered off study
* All patients and/or their parents or legal guardians must sign a written informed consent
* All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human studies must be met