Carbon monoxide desorption from tungsten (100) is studied using angular resolved thermal desorption spectroscopy. The flux of α-CO is found to vary as cos θ, where θ is the angle between the surface normal and the detector centerline, while the flux of β1-CO is found to vary as cos 4θ, the flux of β2-CO is found to vary as cos 3θ and the flux of β3-CO is found to vary as cos θ or cos 2θ. These results suggest that there are rearrangements of the tungsten surface during desorption of β-CO. It is suggested that these arrangements create the three-peak β structure normally observed. The data demonstrate that adsorption and desorption are not necessarily related by microscopic reversability when the adsorption and desorption temperatures are different.