Models indicate that the high heat flow from Io would result in a very thin (approximately 5 km) silicate lithosphere overlying a molten interior, if all heat was transported through the lithosphere via conduction. However, the presence of mountains with relief in excess of 10 km would seem to demand a thick lithosphere, at least locally. A significant fraction of Io's heat flow may be transported via advection through volcanoes. Advective heat transfer permits a thicker lithosphere than does pure conduction, possible reconciling Io's high heat flow with the rugged topography.