Recent biochemical and genetic evidence has shown that carbohydrate-binding protein (CBP-26) is intimately involved in the cell-cell cohesion process. We have isolated a cell-surface-associated receptor molecule for CBP-26 by affinity chromatography. The receptor has a molecular weight of 80,000 daltons. The CBP receptor is constitutively expressed during development. Most significantly, the receptor, when added to aggregation-competent cells, blocks the cells' ability to reaggregate. These results suggest that CBP and its receptor play an important role in the cell cohesion and aggregation process.