As a result of the mode noise of common dye lasers employed in the accumulation of two-photon spectral data, band shapes and peak heights are most often source dependent. If dye laser sources were operated in the single-mode configuration, this dependency would be eliminated. However, such low power devices are incapable of providing useful signal levels for most compounds. By exploitation of the very large two-photon cross section of p-bis(o-methylstyryl)benzene, the source-independent excitation spectrum was determined for both plane and circularly polarized light.