The replicative lifespan of Saccharomyces cerevisiae is determined by both genetic and environmental factors. Many of the same factors determine the lifespan of metazoan animals. The lack of fast and reliable lifespan assays has limited the pace of yeast aging research. In this study we describe a novel strategy for assaying replicative lifespan in yeast, and apply it in a screening of mutants that are resistant to pro-oxidants. The assay reproduces the lifespan-shortening effects of deleting SIR2 and of growth in the presence of paraquat, a pro-oxidant. The lifespan-increasing activity of resveratrol is also reproduced. Compared to current assays, this new strategy promises to significantly increase the possible number of replicative-lifespan determinations.