An investigator proposes a study to determine the clinical relevance of a new technique to quantitate minimal residual disease (mrd) during therapy for acute lymphoblastic leukemia in adolescents. The study requires that two additional bone marrow aspirates be performed during the course of treatment. The subject's treatment will not be altered based in the results of the assay, but if the presence of minimal residual disease is found to predict for higher risk of relapse, future patients with this disease would benefit from improved treatment. This study is approvable only if:.