AbstractThe luminescence processes in several rare‐earth compounds are discussed, viz. sensitization, one‐step energy transfer, multi‐step energy transfer (migration) and trapping. Results are given for compounds containing Eu3 +, Tb3+ and Gd3+. The dimensionality of the rare‐earth sublattice (three, two or one) influences the migration and examples are presented. The case of Eu3+ is the first for which one‐, two‐ and three‐dimensional migration has been observed for one and the same optically active ion. Gadolinium compounds can be applied in luminescent lamps, where they improve the lamp output considerably.