Flow cytometric assays for apoptosis are now in widespread use. The multiparametric nature of flow cytometry allows multiple assays for several apoptotic characteristics to be combined in a single sample, providing a powerful tool for elucidating the complex progression of apoptotic death in a variety of cell types. This chapter describes one such assay, allowing simultaneous analysis of caspase activation, annexin V binding to “flipped” phosphatidylserine residues and membrane permeability to DNA binding dyes. This multidimensional approach to analyzing apoptosis provides far more information than single-parameter assays that provide only an ambiguous “percent apoptotic” result, given that multiple early, intermediate, and late apoptotic stages can be visualized simultaneously. This multiparametric approach is also amenable to a variety of flow cytometric instrumentation, both old and new.