Electronic transitions between f-f orbitals are well known to be parity forbidden. The char- acteristic narrow and sharp lines from the luminescence of lanthanide(III) ions are seen be- cause the presence of a crystal field relaxes the selection rules. Lanthanide(III) ion coordi- nation chemistry does not have the directional bonding found in transition metal complexes because the valence electrons in lanthanide(III) ions are shielded by outer, filled orbitals. Intrinsic properties of each lanthanide(III) ion are therefore determined by the crystal field symmetry, which controls the splitting of the electronic energy levels. Hence, the crystal field perturbation is directly observed with optical spectroscopy. Luminescence spectros- copy is one our best tools to understand the chemistry of the lanthanide(III) ions. Most of the optical spectroscopy done to study the properties of the lanthanides is done in solution. However, determining the solution structure of a lanthanide(III) complex is not simple. Therefore, the main advantage solid-state spectroscopy holds over solution is that in solid state the structure of the complex is known. Information obtained in both media is important in order to fully characterize a complex. Ideally, combining the information derived from each media would optimize what we can learn about each complex. In order to utilize all the information available from each media, the gap between the two methods must be bridged. Going from solution to solid state requires an empirical approach to monitor the changes. First, the metal-ligand interactions for lanthanide(III) ions and various anions in solution were determined by studying europium(III) complexes in water. The luminescence proper- ties of europium(III) ions with common ligands were established to eventually correlate the solution structures with solid-state properties. The transition to solid-state was initiated with crystals of simple, ten-coordinated europium(III) complexes to evaluate the crystal field. The importance of exact determination of the lanthanide(III) ion coordination geometry be- comes clear when even slight deviations from ideal symmetry of the crystal field are directly expressed in the luminescence behavior. The site symmetry of europium(III) ions in crystals was evaluated by our method that builds on the Continues Symmetry Measure approach. The methodology quantifies symmetry as value on a spectrum instead of an ‘either-or’ prop- erty. Thus, the coordination environment of lanthanide(III) ion is assessed by comparison to idealized model structures. Solid-state luminescence spectroscopy allows us to determine the optical properties of known structures. By quantifying the deviation from ideal symmetry, we can improve our understanding of the luminescence properties and correlate the information with solution structures. Combining the information obtained from solid-state spectroscopy of euro- pium(III) complexes with an evaluation of the ion site symmetry is a starting point for fur- thering our understanding of the solution structures of lanthanide(III) ions.