Cadherins are the transmembrane component of adherens junctions found between interacting cells in tissues. The cadherins bind cells to one another in a specific manner and link to the actin cytoskeleton through intracellular catenins. In addition to promoting strong cell-cell adhesion, cadherins appear to initiate and modify intracellular signaling pathways. The loss of E-cadherin function in epithelial cells is thought to be an important step in tumorigenesis. Moreover, anomalous expression of inappropriate cadherins in epithelial cells alters their behavior and may contribute to the tumorigenic phenotype. For breast cancer the decreased expression of E-cadherin alone may have limited value as a prognostic indicator; however, examining the repertoire of cadherins and catenins expressed by tumors may provide useful prognostic information.