Emission spectra have been recorded of polycrystalline samples of Na7EuIIIW10O35·xH2O and K13EuIII(SiW11O39)2·xH2O. The fluorescence of the europium ion can be efficiently pumped via the internal states of the tungstate groups. The cluster maintains its integrity in neutral aqueous solution, in which the europium ion also luminesces intensely. The symmetry of the crystal field surrounding the lanthanoid ion has been assigned by an analysis of the Stark splittings seen in the 5D0→7FJ emission lines. The praseodymium(III), neodymium(III), and holmium(III) analogues of Na7EuIIIW10O35·xH2O do not give enhanced fluorescence under excitation in the poly-tungstate bands, but emission could be detected by direct laser excitation of the f-f states. An analysis of the praseodymium spectrum has been attemmpted, but overlapping of transitions prevents an unambiguous assignment of the Stark splittings.