Aging is the major common risk factor for the diseases that most burden human populations. Remarkable progress in the biology of aging and animal models supports the geroscience hypothesis: by targeting aging biology the onset of age-related diseases and other aging phenotypes can be delayed. We are now ready to test this hypothesis clinically, to determine if interventions on the fundamental processes of aging can prevent the accumulation of multiple age-related diseases and other aging phenotypes in older men and women. This presentation describes development of a randomized placebo-controlled clinical trial designed to evaluate whether by targeting the underlying biology of aging using the anti-diabetic drug, metformin, it is possible to reduce the onset of multiple age-related health conditions simultaneously. The design of TAME (Targeting Aging with MEtformin) was the result of a process of engagement with the scientific community, and regulatory and funding authorities that unfolded over several years. If successful, TAME would provide a model for the testing and approval of drugs targeting the fundamental processes of aging rather than targeting disease-specific pathways.