Dr. Gill's research is directed towards understanding the mechanisms underlying the development of functional decline and disability among community-living older persons and towards developing preventive strategies to forestall the onset and progression of disability among those who are most vulnerable. The results from the Yale Precipitating Events Project (PEP), Dr. Gill's ongoing NIA-funded cohort study, which includes monthly assessments of functional status for over 24 years, are revolutionizing our understanding of disability, a problem of immense importance to older persons, their families, and society. In a landmark clinical trial, Dr. Gill's research group demonstrated that functional decline among frail older persons can be prevented through a prehabilitation program targeting underlying impairments in physical capabilities.