Inclusion Criteria:

* Patients must be enrolled on a Children's Oncology Group (COG) ALL Classification Study (AALL08B1) prior to enrollment on AALL0631
* Patients must be \< 366 days of age at the time of diagnosis; for neonates in the first month of life, patients must be \> 36 weeks gestational age at the time of diagnosis
* Patients must be newly diagnosed with acute lymphoblastic leukemia (ALL) or acute undifferentiated leukemia (AUL); patients with T-cell ALL are eligible; patients with bilineage or biphenotypic acute leukemia are eligible, provided the morphology and immunophenotype are predominately lymphoid
* Patients must be previously untreated with the exception of steroids and intrathecal chemotherapy; no other systemic chemotherapy may have been administered; patients receiving prior steroid therapy are eligible for study; any amount of steroid pretreatment will not affect initial induction assignment as long as the patient meets all other eligibility criteria; IT chemotherapy per protocol is allowed for patient convenience at the time of the diagnostic bone marrow or venous line placement to avoid second lumbar puncture; (note: the central nervous system \[CNS\] status must be determined based on a sample obtained prior to administration of any systemic or intrathecal chemotherapy, except for steroid pretreatment); systemic chemotherapy must begin within 72 hours of this IT therapy
* 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
* Patients with mature B-cell ALL or acute myelogenous leukemia (AML) are NOT eligible
* Patients with Down syndrome are NOT eligible