Child and adolescent patients who are diagnosed with acute lymphoblastic leukemia (ALL), both of B-cell or T-cell phenotype, have excellent outcomes when treated with various multiagent chemotherapy regimens. The presentation and early medical management of these young patients are remarkably similar to the initial management of newly diagnosed adult ALL patients, though the eventual chemotherapy may be quite different. Subgroups of childhood and adolescent ALL with poor prognosis are now regularly recognized by cytogenetic and molecular studies as well as by flow cytometry. Minimal residual disease measured at various times in therapy is highly prognostic and may be used to guide therapy. Very high risk patients as well as patients with relapsed or refractory disease may benefit from newer antibody and cell therapies.