This article describes a multistate population-based surveillance system for monitoring sudden unexpected infant deaths (SUIDs) known as the SUID Case Registry pilot program. The pilot program represents collaboration between the Centers for Disease Control and Prevention and the National Center for Child Death Review (NCCDR), which is funded by the Health Resources and Services Administration. The SUID Case Registry builds on existing child death review system activities and protocols. The objectives of the SUID Case Registry are to collect accurate and consistent population-based data about the circumstances and events associated with SUID cases, to improve the completeness and quality of SUID case investigations, and to use a decision-making algorithm with standardized definitions to categorize SUID cases. States who participate in the pilot program commit to review all SUID cases in their state by using their multidisciplinary state and local child death review teams. These teams request and review data from death scene investigators, medical examiners and coroners, law enforcement, social services, pediatric and obstetric providers, and public health per usual, but as part of the pilot program, supplement their SUID case reviews by discussing additional medical, environmental, and behavioral factors, and entering this data using the NCCDR Web-based Case Reporting System. This new surveillance system aims to improve knowledge of factors surrounding SUID events and improve investigation practices. The surveillance system will allow researchers and program planners to create prevention strategies and interventions, ultimately reducing SUIDs and injury-related infant deaths.