Quantitative suspension array technology allows the simultaneous measurement of different cytokines and chemokines in small sample volumes. The possibility of measuring multiple variables is important for discovery of biomarkers of pathogenesis or protection in complex diseases as well as measurement of antigen-specific cellular responses. Measurements can be made in biological specimens, such as plasma or serum, cell culture supernatants, and others. This technology is based on a capture-detection sandwich-type assay using fluorescent microspheres analyzable by Luminex instruments or flow cytometers. The complexity and cost of producing highly multiplexed cytokine/chemokine in-house assays make them especially apt for commercial production. There are several commercial kits available that vary in absolute cytokine concentration, sensitivity, reproducibility, and cost. This chapter gives an overview of cytometric bead array technology, introduces some of the kits, and provides detailed information about the one that performed well in a comparative study (Cytokine Human Magnetic 30-Plex Panel from Life Technologies™).