A theoretical analysis of the factors which contribute to the hygroscopic growth of atmospheric aerosols is presented within the context of the climatic impact of these aerosols. It is found that the factor which most influences the growth factor is the position of the initial dry aerosol size distribution relative to the efficient light scattering particle size range. When this factor is taken into consideration, rural aerosols have much larger growth factors than those currently utilized in assessment of the climatic impact of atmospheric aerosols. ¿ American Geophysical Union 1993