It is well known that incorporation of lime amendments into mine wastes is an effective treatment to neutralize active and potential acidity, thereby reducing soluble metals and facilitating plant growth. Many of these same wastes contain arsenic. Studies have shown that, in general, the solubility of arsenic (a metalloid) increases with increasing pH. However, a number of laboratory and field studies with mine waste have shown decreased solubility of arsenic with increasing pH. These studies have not identified what factors are influencing the fate of arsenic in these mine wastes, nor determined the mechanisms involved in reducing the soluble arsenic. This research project evaluated the physical, chemical, and morphological factors affecting a decrease in soluble arsenic concentrations upon liming and whether characteristics of an unamended waste can be used to determine the mobility of arsenic in the amended waste. Testing a mine waste for the parameters soluble Fe plus Al plus Mn; percent clay; total lime requirement; arsenic oxyanions; sequential extraction of metals; mineralogy; soluble Ca and Ni; and potentially EC and CEC/AEC will enable prediction of the potential fate of arsenic following liming of an arsenic-laden, acidic-metalliferrous mine waste. However, interactions between parameters are complex, and a straightforward protocol is not readily developed. The need for site specific testing is strongly emphasized.