We combined scanning tunneling microscopy and x-ray photoelectron spectroscopy experiments with density-functional theory calculations to study dispersed tungsta clusters on anatase TiO2(101). Following two different preparation methods, we found that monomeric WO3 species are the most stable configuration rather than WO3 trimers, (WO3)3. The WO3 monomers form tetrahedral WO4 structures on anatase TiO2(101), with one W-O bond and two W-O-Ti linkages per WO3 monomer. Locally, the WO3 monomers form well-ordered (2 × 1) structures. The discovered geometric structure of WO3 on anatase TiO2(101) opens up numerous opportunities for fundamental studies addressing tungsta and accurate structure-activity studies of WO3/TiO2 model catalysts.