Abstract: The present invention provides compositions and methods to facilitate the identification of compounds that are capable of interacting with a biological macromolecule of interest. In one aspect, a composition is provided that comprises an array of one or more types of chemical compounds attached to a solid support, wherein the density of the array of compounds is at least 1000 spots per cm2. In particularly preferred embodiments, these compounds are attached to the solid support through a covalent interaction.