Although cellular senescence drives multiple age-related co-morbidities through the senescence-associated secretory phenotype (SASP), in vivo senescent cell identification remains challenging. Here, we generated a gene set (SenMayo) and validated its enrichment in bone biopsies from two aged human cohorts. We further demonstrated reductions in SenMayo in bone following genetic clearance of senescent cells in mice and in adipose tissue from humans following pharmacological senescent cell clearance. We next used SenMayo to identify senescent hematopoietic or...