The electron affinity of lanthanum has been measured using laser photoelectron energy spectroscopy. This is the first electron affinity measurement for lanthanum and one of the first measurements of an electron affinity of a rare-earth series element. The electron affinity of lanthanum was measured to be . At least one bound excited state of was also observed in the photoelectron spectra, and the binding energy relative to the ground state of lanthanum was measured as . The present experimental measurements are compared to a recent calculation.