Presently, phosphors and luminescent materials for lighting, telecommunications, displays, security inks and marking, as well as for probes in biosciences represent one third of the total value of the lanthanides used worldwide. If optical glasses and laser materials are added, this figure is close to 40%, explaining the large interest that the scientific community is devoting to such materials. The present review focuses on the design of highly luminescent lanthanide complexes and discusses all aspects needing optimization. Reference is made to the mastering of the various energy migration processes in luminescence sensitization by organic ligands, to minimizing non-radiative deactivation mechanisms, as well as to other parameters such as the radiative lifetime, the refractive index, and the benefit of inserting luminescent complexes into inorganic-hybrid structures. Comparative tables list the most luminescent complexes emitting in the visible and near-infrared ranges and the best chromophores are pointed out. (C) 2014 Elsevier B.V. All rights reserved.