The caspase-1 enzymatic activity plays a major role in the innate immune response as it regulates the maturation of two major proinflammatory cytokines, the interleukin-1beta (IL-1β) and IL-18. In this chapter, we describe the technique of Western blot to assess caspase-1 activation. This method provides multiple information within one experiment. It allows the detection of both unprocessed and processed caspase-1 and substrates.