This review focuses on the most recent advances in the diagnostic and prognostic work-up of adult acute lymphoblastic leukemia (ALL), and on their implications in the clinical management of the disease. Over the years, information obtained through extensive immunophenotyping, karyotyping, molecular genetics, multidrug resistance and, more recently, genomic profiling is progressively contributing to a better understanding of the biology of this complex disease, to the identification of subgroups of patients with different clinical outcomes, to a more precise monitoring of minimal residual disease, to the use of different therapeutic protocols based on prognostic indicators and, finally, to the design of innovative and specific treatment strategies. The next few years will tell us if this biologically-guided approach, which is progressively individualizing the management of adult ALL patients, will ultimately impact on the prognosis of a disease that has stagnated over many decade.