Application of flow cytometry to the study of cell death has three goals: identification and quantification of dead and dying cells; discrimination between apoptotic and necrotic modes of cell death; and elucidation of mechanisms involved in cell death. This massively detailed unit by a pioneer in the field brings together the most common flow cytometric methods for the study of apoptosis, covering a wide variety of apoptotic indices, from loss of membrane potential, caspase activation, and phosphatidyl exposure to DNA fragmentation and tissue transglutaminase activation. The authors also present their recently developed protocol, analogous to the FLICA approach for caspases, for the detection of serine proteases ('serpases'). The protocols are accompanied by extensive commentary discussion of applicability, strategic planning, problems, and pitfalls, plus a comprehensive list of references.