The relative binding sites of dengue serotype-specific, dengue subcomplex-specific, dengue complex-specific, flavivirus subgroup-reactive, and flavivirus group-reactive monoclonal antibody preparations were identified by using competitive antibody binding assays. A dengue complex-specific epitope, capable of mediating infection enhancement, was identified on a 20,000 dalton protein found on intracellular virions. The other epitopes were assigned relative positions on the E glycoprotein by competitive antibody binding. These could be grouped into 3 linkage groups based on the ability of some monoclonal antibodies to block contiguous binding sites. Some antibodies were able to increase or "promote" the binding of antibodies from other linkage groups. These results suggest that a continuum of antigenic reactivities exist on the E glycoprotein of the dengue viruses, and that the conformation of this glycoprotein may be altered after antibody binding.