Recognition and binding between cells are of fundamental importance for a proper function of multicellular organisms, both during embryonic development and in the adult stage. Recently several cell surface proteins that are involved in these phenomena have been discovered. In the identification of these proteins, called cell adhesion molecules (CAMs), immunological methods have played a significant role. In a different approach to studies of cell-cell binding at the molecular level, the chemical composition of intercellular junctions is being studied. Intercellular junctions are specialized cell surface domains that have been identified by electron microscopy. They are particularly well developed in epithelia. Several proteins in the junctions have now been identified and characterized. This review deals with the biochemical properties of epithelial CAMs, and those proteins that are candidates for cell-to-cell binding in the junctions. In particular, the relationships between the various CAMs and junctional proteins are discussed. The tentative biological functions of these molecules are also considered.