ABSTRACT The Washington National Primate Research Center (WaNPRC) provides infrastructure and research support for a large number of biomedical research projects utilizing nonhuman primates (NHP) as models for human disease. Current housing guidelines, regulations and standards require that research facilities provide social housing for all NHPs unless there are scientific or veterinary exemptions. Many of the research protocols at the WaNPRC allow for social housing and others allow for social interactions at least for a portion of the study without compromising experimental outcomes. Socialization of NHP can be challenging due to several factors and facility constraints. To address the challenges, we have designed an innovative modular caging system that is flexible enough to facilitate socialization of NHP housed at the center. However, there are insufficient numbers of these new modular cages to provide social housing for animals currently on study and for our funded facility expansions. Therefore, this proposal seeks support to purchase additional caging to comply with the new requirements. The new NHP caging will replace old-style cages and provide additional cages for our scheduled renovation of our Western facility and the proposed ARC building. In order to increase our holding capacity and compliance with regulation, we need to purchase many new cages. This grant would allow is to purchase 50 modular stainless steel primate enrichment units (100 cages). The proposal specifically requests the purchase of 27 Group 3 rack units (54 cages) and 23 Group 4 rack units (46 cages). Funding from this proposal would greatly enhance our ability to socially house additional macaques for critical biomedical research projects.