The mission of the Division of AIDS (DAIDS), National Institute of Allergy and Infectious Diseases (NIAID) is to ensure an end to the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic by supporting research that can lead to the development of therapies, vaccines, and prevention strategies. Nonhuman primate (NHP) models present the opportunity to test a variety of candidate AIDS vaccines, optimizing their ability to elicit immune responses and testing their ability to prevent infection or to control virus replication after virus challenge. DAIDS provides immunological and virological support for NHP studies conducted at NIAID’s Simian Vaccine Evaluation Unit (SVEU) contract sites and by AIDS vaccine researchers through three Nonhuman Primate Immunology and Virology Laboratories for AIDS Vaccine Research and Development (NHP Core Labs) contracts. The objective of these Core Laboratories has been to ensure standardization and comparability of the assays conducted for preclinical NHP studies and to provide a common basis for assessment of the immunogenicity and efficacy of candidate HIV and SIV vaccines.