Laboratory experiments were conducted to evaluate the sorptivity of cesium onto Los Alamos soils under controlled experimental conditions. Four soil profiles were collected and each soil profile which is broken into layers according to previously identified soil horizons were studied. Batch sorption isotherms were studied to quantify the chemical reactivity of each soil horizon toward cesium ion. Radioactive cesium-137 was used as sorbent and gamma counting was used to quantify the amount of sorption. Desorption experiments were conducted after the sorption experiments. Batch desorption isotherms were studied to quantify the desorption of presorbed cesium from these Los Alamos soils. This study suggests cesium may sorb strongly and irreversibly on most Los Alamos soils. The amount of cesium sorption and desorption is possibly related to the clay content of the soil sample since subsurface sample has a higher clay content than that of surface sample.