Light sources that emit light having enhanced color spectrum characteristics are described. A color metric called the Lighting Preference Index (LPI) is disclosed that enables quantitative optimization of color preference by tailoring the spectral power distribution of the light source. In an embodiment, a lamp includes at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm, at least one green or yellow-green light source having peak wavelength in the range of about 500 nm to about 580 nm, and at least one red light source having peak wavelength in the range of about 600 nm to about 680 nm, wherein the lamp has an LPI of at least 120.