Arsenic (As) is an element of great concern because of its potential to harm human health and the environment. Competition between As and P for adsorption sites in soil can be a limiting factor to evaluate As bioavailability and transport within the soil. Ultisols are known for their moderate to high P fixation capacity to amorphous and microcrystalline iron and aluminum oxyhydroxides.  The effect of fixed P on As mobility is largely unknown. This study evaluates adsorption-desorption mechanisms of various As species (arsenite, arsenate) in soils that have low and high levels of P due to consistent long-term P management strategies using batch experiments. Results indicate that As sorption is a function of As species, P level in the soil, and soil pH. Arsenate adsorption was greater than arsenite at all pH and soil P levels.  With increasing soil P concentration, rates of As adsorption decreased indicating competition between As and P for high P soils. Maximum adsorption occurred at pH 4.5. The results indicate that competitive sorption between As and P can be modeled to predict As mobility from soils receiving different P inputs.