OUTLINE: Patients receive induction therapy on weeks 1-4. This consists of oral prednisone three times a day on days 1-28; vincristine IV on days 1, 8, 15, and 22; daunorubicin IV on days 8, 15, and 22; and asparaginase IM on days 2, 5, 8, 12, 15, and 19. Patients also receive methotrexate intrathecally (IT) on days 1 and 8. Patients with CNS 2 and 3 disease also receive methotrexate IT on days 15 and 22. Patients who achieve M2 bone marrow on day 29 receive oral prednisone three times a day on days 29-42; vincristine IV and daunorubicin IV over 15 minutes on days 29 and 36; and asparaginase IM on days 29, 32, 36, and 39. If bone marrow is M3 on day 29 or M2 or M3 on day 43, then patient is off study. Patients proceed to consolidation therapy on weeks 5-25. This consists of high dose methotrexate IV over 24 hours on weeks 6, 8, 16, and 18, followed by leucovorin calcium IV or orally every 6 hours for 5 doses; oral mercaptopurine on weeks 6-9 and 16-19; cytarabine IV over 6 hours followed by idarubicin IV over 15 minutes for 4 days; and filgrastim (G-CSF) subcutaneously (SQ) beginning on day 5 and continuing for about 10-14 days on weeks 10 and 20. Patients receive etoposide IV over 1 hour followed by cyclophosphamide IV over 10 minutes for 5 days and G-CSF SQ beginning on day 6 for 10-14 days on weeks 13 and 23. Methotrexate IT is administered on weeks 6, 8, 13, 16, 18, and 23. Patients then proceed to continuous intensification therapy during weeks 26-61. Patients receive vincristine IV, daunorubicin IV, and methotrexate IT on day 1, and oral dexamethasone twice a day on days 1-7 on weeks 26, 32, 38, 44, 50, and 56. Patients also receive high dose cytarabine IV over 1 hour, every 12 hours, for 4 doses, followed by asparaginase IM 3 hours after the last dose of cytarabine, on weeks 27, 33, 39, 45, 51, and 57. Oral mercaptopurine and methotrexate IM are administered on day 1 during weeks 29, 31, 35, 37, 41, 43, 47, 49, 53, 55, 59, and 61. Patients receive etoposide IV over 1-2 hours followed by cyclophosphamide IV during weeks 30, 36, 42, 48, 54, and 60. Patients then proceed to continuation therapy during weeks 62-126. Vincristine IV and cyclophosphamide IV are administered on weeks 62-65, 70-73, 78-81, 86-89, 94-97, 102-105, 110-113, and 118-121. Patients also receive oral dexamethasone twice a day for 7 days on weeks 62, 70, 78, 86, 94, 102, 110, and 118, and cytarabine IV on weeks 63, 65, 71, 73, 79, 81, 87, 89, 95, 97, 103, 105, 111, 113, 119, and 121. Oral mercaptopurine is administered daily during weeks 66-69, 74-77, 82-85, 90-93, 98-101, 106-109, 114-117, and 122-125 and methotrexate IM on weeks 66-69, 74-77, 82-85, 90-93, 98-101, 106-109, 114-117, and 122-125. Methotrexate IT is administered during weeks 62, 70, 78, 86, 94, 102, 110, and 118. Patients who are CNS 3 at diagnosis receive whole brain irradiation beginning at week 62 along with the first course of continuation therapy. These patients do not receive any methotrexate IT after week 62. Patients are followed monthly for 1 year, every 2 months for 1 year, every 3 months for 1 year, every 6 months for 1 year, then annually thereafter.