Abstract: The present invention provides immunogenic oligosaccharide compositions and methods of making and using them. In particular, the compositions comprise native O-linked and S-linked oligosaccharides coupled to a protein carrier via a linker, wherein the resultant conjugate elicits a protectively immunogenic response, particularly in vaccines against pathogenic Candida species and more particularly against Candida albicans. Preferably the pathogenic Candida species are those that possess cell wall oligosaccharide compositions similar to the ?-mannan component of Candida albicans cell walls.