Self-incompatibility in Brassica is controlled by a single, highly polymorphic locus that extends over several hundred ki-lobases and includes several expressed genes. Two stigma proteins, the S locus receptor kinase (SRK) and the S locus glycoprotein (SLG), are encoded by genes located at the S locus and are thought to be involved in the recognition of self-pollen by the stigma. We report here that two different SLG genes, SLGA and SLGB , are located at the S locus in the class II, pollen-recessive S 15 haplotype. Both genes are interrupted by a single intron; however, SLGA encodes both soluble and membrane-anchored forms of SLG, whereas SLGB encodes only soluble SLG proteins. Thus, including SRK , the S locus in the S 15 haplotype contains at least three members of the S gene family. The protein products of these three genes have been characterized, and each SLG glycoform was assigned to an SLG gene. Evidence is presented that the S 2 and S 5 haplotypes carry only one or the other of the SLG genes, indicating either that they are redundant or that they are not required for the self-incompatibility response.