Central nervous system (CNS) therapy begins immediately after the end of the induction therapy. This phase of treatment should last 3 weeks. Treatment includes a series of spinal taps with the instillation of anti-leukemia drugs. Four spinal taps will be performed over a two week period. Anti-leukemia drugs will also be given orally. The drugs given are as follows: Vincristine; on day 1: Doxorubicin; on day 1: 6-mercaptopurine (6-MP); on days 1-14: Intra-thecal Methotrexate/Cytarabine; 4 times over 2 weeks.