Adhesion G protein-coupled receptors (GPCRs) are so named because they have domains that are common to proteins involved in cell adhesion. Some examples include EGF-like, leucine-rich, thrombospondin, lectin-like, and cadherin repeat domains. This receptor family is defined by a large extracellular region linked to a seven-transmembrane-spanning domain (TM7) via a stalk region containing a GPCR proteolytic site (GPS). The GPS within these receptors undergoes an autoproteolytic reaction, yielding an extracellular alpha-subunit and a TM7 beta-subunit. Although adhesion-GPCRs as a whole are expressed ubiquitously, individual receptors are generally highly tissue and/or cell type specific. Consequently, this family of receptors has diverse roles in many areas of biology including immunology, development, and tumorigenesis.