The purpose of this Notice of Funding Opportunity (NOFO) is to support SenNet Discovery and Validation Centers (SenNet DVCs) as a core component of Stage 2 of the NIH Common Fund Cellular Senescence Network (SenNet). Building on Stage 1 resources, DVCs will define, refine, and validate tissue- and disease-relevant cellular senescence signatures (“senotypes”) and associated biomarkers, and will investigate their functional consequences in human health and disease. DVCs are expected to generate and contribute high-quality molecular, cellular, and spatial datasets (including relevant metadata and documentation) and to use complementary experimental systems, as appropriate, to validate senotypes/biomarkers and characterize responses to senescence-associated perturbations or senotherapeutic approaches. DVC applications should also propose goals and aims for SenNet consortium-wide organizational and outreach activities (SenNet OOC functions).