Abstract: Dendritic polymers containing disulfide functional groups which are essentially inert under non-reducing conditions, but which form sulfhydryl groups upon being subjected to a reducing agent are prepared by synthesizing dendritic polymers having a core with a disulfide linkage or by reacting a dendritic polymer with a molecule containing a disulfide linkage and reactive terminal groups. In one aspect of the invention, dendritic polymers having a single disulfide functional group at the core are provided. The single disulfide group at the core can be reduced to form two sulfhydryl groups to which other molecules, such as proteins, oligonucleotides, peptides, hormones, other dendritic polymers, non-dendritic polymers, etc., can be bound.