Elevation of the calcium concentration in keratinocyte culture induces the rapid organization of adherens junctions and desmosomes. Formation of these intercellular junctions is accompanied by reorganization of the cytoskeleton and, with a more delayed timecourse, stratification of the culture into a multilayered epithelial cell sheet. Keratinocytes express two cadherins, known as E- and P-cadherin, which are the cell-cell adhesion molecules of the adherens junction. Antibody that blocks E-cadherin function delays the calcium-induced formation of both adherens junctions and desmosomes and leads to an abnormally stratified cultured. In the present study, we show that anti-E-cadherin plus anti-P-cadherin antibodies inhibit the formation of adherens junctions and desmosomes, prevent reorganization of the cytoskeleton, and block stratification. These studies indicate that cadherin function is required for the calcium-induced intercellular junction organization and stratification of human keratinocytes in vitro.