Proteases are now firmly established as major regulators of the “execution” phase of apoptosis. Here, we examine the role of proteases and their relationship to ceramide, a proposed mediator of apoptosis, in the tumor necrosis factor-α (TNF-α)–induced pathway of cell death. Ceramide induced activation of prICE, the protease that cleaves the death substrate poly(ADP-ribose) polymerase. Bcl-2 inhibited ceramide-induced death, but not ceramide generation. In contrast, Cytokine response modifier A (CrmA), a potent inhibitor of Interleukin-1β converting enzyme and related proteases, inhibited ceramide generation and prevented TNF-α–induced death. Exogenous ceramide could overcome the CrmA block to cell death, but not the Bcl-2 block. CrmA, however, did not inhibit the activation of nuclear factor (NF)-κB by TNF-α, demonstrating that other signaling functions of TNF-α remain intact and that ceramide does not play a role in the activation of NF-κB. These studies support a distinct role for proteases in the signaling/activation phase of apoptosis acting upstream of ceramide formation.