The enhancements of sodium atomic-absorption and emission by methyl-, ethyl-, and propyl-alcohol of various concentrations were studied under identical conditions with a modified Zeiss Model Ⅲ flame photometer. The spray rate, the effective spray rate (i.e., the amount of spray reaching the flame per unit time), the flame temperature, and the surface tension and viscosity for various alcohol-water solutions were measured, and a possible mechanism of the enhancements was suggested. According to this mechanism, it was shown that although the enhancement in absorption results mainly from an increase in the effective spray rate, but for alkali metals, which have low ionization potentials, the reduction of the degree of ionization due to the lowering of the flame temperature also plays a definite role. As for the enhancement in emission, it was shown that in addition to the changes in effective spray rate and degree of ionization, the change in the Boltzmann factor exp(-Ei/kT) should also be taken into account.