When and why do cells die? Does the concentration of environmental pollutants exert cytotoxic or cytostatic effects on cells? What factors influence the rate and timing of cell proliferation? Researchers in basic, industrial, and medical research are asking these questions and looking for answers. Understanding the normal regulation of cell death and cell proliferation will be critical e.g., for the development of new and more successful therapies for preventing and treating cancer and for the screening of new anti-cancer compounds.Many assays exist to measure cell death and cell proliferation. However, if you have only recently become interested in cell death or cell proliferation, you may find the diversity of such assays bewildering. You may not be able to determine what each assay measures nor decide which assays are best for your purposes. This guide is designed to help you make such decisions. It presents a brief overview of cell death and cell proliferation, along with the major assays currently available to measure each. In addition, it clearly lists the advantages and the disadvantages of these assays.For those who want to eliminate radioactivity from their laboratories, this review also describes a number of non-radioactive assays that can serve as alternatives to radioactive assays. Wherever possible, the review will compare the sensitivity of the radioactive and non-radioactive assays.