The functions of many glycans in biological systems involve their interactions with relevant carbohydrate (glycan)-binding proteins (CBPs or GBPs). Protein-glycan interactions are therefore extremely important and dependent on the structures of both proteins and glycans. Glycan microarrays (Feizi et al. 2003; Horlacher and Seeberger 2008; Paulson et al. 2006; Smith et al. 2010; Stevens et al. 2006), in which many glycan structures are presented simultaneously in a single microscope slide or chip for interrogation with labeled GBPs and microorganisms, have become very popular during the last decade largely due to the public availability of a large glycan array developed by the Consortium for Functional Glycomics (CFG). This platform of over 600 structurally deˆned glycan targets is a high-throughput tool to quickly explore the glycan-binding speciˆcities of GBPs and microorganisms. This chapter serves as an overview of the development and application of this widely used technique.