A plethora of genetic, dietary, and pharmacological interventions can extend healthy lifespan in laboratory animals and can delay or ameliorate diverse aging-related diseases. Mechanisms of aging are conserved in evolution, and discoveries made in animals are informing our understanding of human aging. This raises the intriguing possibility of performing preventative medicine against chronic and age-related diseases, by targeting their main risk factor, namely aging. Important current challenges in the field are (1) to understand the downstream pathways by which longevity interventions can combat age-related loss of function and pathology, (2) to evaluate the impact of regenerative interventions and cellular reprogramming on age-related diseases, and (3) to translate the findings into the extension of human health span. This fourth meeting will continue to explore these topics, with particular emphasis on what we can learn from variation in the rate of ageing in the natural world, mitochondria, cellular senescence, biomarkers and epidemiology, immune aging and reprogramming and rejuvenation strategies.