Studies of aging in the nematode Caenorhabditis elegans have revealed a relationship between stress resistance and the rate of aging: Mutations which extend mean and maximum life-span also confer resistance to thermal stress. We review the molecular genetics of aging in C. elegans and introduce methods for obtaining novel mutants which display altered aging rates. We present the use of the "surrogate" phenotype of thermotolerance to develop a selection for novel mutations which slow aging.