The Sudden Death in the Young (SDY) Initiative is a two-phase program to explore and provide greater understanding of SDY. During the first phase of the program, NHLBI is obtaining services from CDC for the development of a surveillance system and registry that will broaden and enhance the activities of the National Center for Child Death Review (http://childdeathreview.org/) and the Sudden Unexpected Infant Death (SUID) Registry (www.cdc.gov/SIDS/). This will result in the first prospective, population-based data set compiled for the comprehensive evaluation of SDY in the United States. The SDY Registry will include data from death certificates, medical records, death scene investigations, and pathology reports. In addition, a serum sample for DNA extraction will be collected from a subset of cases. It will provide the opportunity to estimate incidence more precisely than any previous study and to establish an infrastructure for future expanded use. After establishment of the registry, the CDC will enter into an Intra-Departmental Delegation Authority (IDDA) with NHLBI to assist NHLBI with the award and administration of NHLBI grants to state public health agencies to collect data for the registry.