The multidisciplinary team of pediatric oncology investigators at the Mount Sinai School of Medicine (MSSM) will interact as a single pediatric oncology group in order to: (1) continue their collaborative participation with the Pediatric Oncology Group (POG) in cooperative programs to determine the optimal treatment regimen for infants, children and adolescents with leukemia and solid tumors; (2) collect precise data by high quality performance and adherence to protocol procedures and record keeping; (4) participate in modality and disease oriented subcommittees of POG to develop multidisciplinary studies of therapy for childhood cancer; and (5) help develop within the Mount Sinai School of Medicine laboratories that will be utilized by the investigators within POG to better understand to biology and pathophysiology of childhood cancer.