The Yellowstone hot spot has been identified mainly by its track of age-progressive volcanics; many smaller scale tectonic features serve to hide the long-wavelength hot spot-related swell. By employing averaging and filtering techniques, we are able to identify a swell in both the gravity and topography and use them to constrain the apparent depth of compensation of the Yellowstone hot spot at 70¿10 km. This value is comparable to the deepest compensation depths for swells on old oceanic lithosphere. A compensation depth within the mid- to lower lithosphere combined with the only 15 m.y. known duration of the hot spot suggests either dynamic thinning of the thermal plate of compensation by upwelling in a low-viscosity asthenosphere, with some combination of the two explanations being consistent with seismic tomography results. Thus in many ways the Yellowstone hot spot appears quite similar to the oceanic analogues. ¿ American Geophysical Union 1994