One of the main goals of the annual Tandem Blood and Marrow Transplantation meeting is to provide an outstanding educational experience for the attendees. Each year the Program Committee selects topics and speakers designed to sharpen our thinking about the major issues in our field, so that we can return to our respective centers energized to better help our patients overcome the challenges they face. This year’s program addresses some topics that have never been previously addressed at a Tandem meeting, while updating the status of some thorny problems that continue to consume considerable attention. The 2012 Education Supplement on Hematopoietic Cell Transplantation is provided as a resource for attendees to complement the presentations at the meeting. Among the topics covered in this year’s supplement are new insights into the clinical relevance of natural killer cells, next-generation sequencing, the interleukin-17 pathway, tolerance, and graft-versus-host disease (GVHD) biomarkers. Considerations for transplantation in the elderly patient, a rapidly increasing hematopoietic cell transplant population, are reviewed. The evidence behind donor selection when only mismatched unrelated, haploidentical related, or unrelated cord blood sources are available is discussed in detail. Posttransplantation complications that are major concerns for patients and caregivers alike, such as chronic GVHD, second malignancies, cognitive functioning, and poor stamina, are updated with the latest information on biology and therapeutic interventions. New information relevant to the treatment of patients with myeloma, leukemia, lymphoma, neuroblastoma, and nonmalignant disorders are discussed. The data to support an emerging application, transplantation for the treatment of multiple sclerosis, is summarized as is the approach to patients who have HIV infection. An excellent point–counterpoint debate over the use of anti-T cell antibodies is presented, along with a summary of newer therapies for GVHD. Last year’s nuclear accident in Japan highlights the timeliness of an update of the role of the transplant team in the case of radiation disasters. Last, and highly relevant to our field, the optimal approach to clinical trial design for rare diseases is presented. Taken together, this supplement represents a comprehensive overview of some of the most important issues in the field of hematopoietic cell transplantation today. The opportunity to provide this supplement to the readers is due to the dedication and willingness of the authors to complete yet one more task in their busy lives. On behalf of the American Society for Blood and Marrow Transplantation and the Center for Blood and Marrow Transplant Research, the editors would like to thank all the authors for their excellent articles. We also would like to thank the associate editors for their careful reviews and, importantly, their adherence to the necessary timeline.