The local structure around luminescent lanthanide ions inside a nanoparticle will be investigated by the synchrotron based techniques EXAFS and HEXS, as well as by UV-vis-NIR absoroption and luminescence spectroscopy. The knowledge about the local symmetry, the number of neighboring ions and the distance to the central lanthanide ion will be related to the luminescence performance of the nanoparticle, in order to optimize synthetic pathways to develop superior nanophosphors.