High-Throughput Screening (HTS) requires the miniaturization and automation of In Vitro bioassays so that millions of variables can be tested. HTS is often an important step in the discovery of new medicines. The Rockefeller University HTS Center (HTSRC) exists to aid in the search for small molecule or genetic modulators of biological functions. The center has a library of 165,000 compounds and a collection of 91,635 human siRNA's spanning the entire genome. The center is configured for processing 96, 384 and 1536-well microtiter plates through the use of automated changeable tip dispensers, non-contact dispensers, syringe dispensers and pin tools. For assay technologies, the HTS Center has the capability to support cellular and biochemical assays using absorbance, fluorescent kinetics, fluorescence anisotropy, time-resolved fluorescence, time-resolved fluorescence resonance energy transfer, AlphaScreen, bioluminescence, scintillation proximity and cellular fluorescence imaging. Assay targets can include ion channels, receptors, enzymes, protein interactions, signaling pathways and cellular processes.