A white-light electro-luminescent lamp having an adjustable spectral power distribution, including a first light-emitting element which emits light within each of three wavelength bands, 1) between 440 and 520 nm, 2) between 520 and 600 nm, and 3) between 600 and 680 nm. A second light-emitting element emits light within each of three wavelength bands, 1) between 440 and 520 nm, 2) between 520 and 600 nm, and 3) between 600 and 680 nm. A controller modulates the integrated spectral power of the light produced by the first and the second light-emitting elements such that the spectral power distribution of the light formed by combining the light produced by the modulated first and second light-emitting elements is substantially equal to a CIE standard daylight spectral power distribution for correlated color temperatures between 4000K-9500K.