We examine the conditions necessary to form aeolian features on planets such as ripples and dunes. Specifically, we compute saltation and suspension speeds for the terrestrial planets, Triton, Titan, and two possible primordial Titan atmospheres, and compare these with theoretical estimates of friction speeds. We examine the availability of sediments and the mass transport rates needed to form aeolian features on Titan, and compare likely feature dimensions with the resolution of instruments on the Cassini mission to evaluate the detectability of such features. A novel element is the consideration of a Weibull wind speed distribution, adding a probabilistic element to the formation and destruction of dunes. We find dunes unlikely to form in any Titan atmospheres, suggesting that dunelike bedforms are only likely to be found in areas that were once submerged by liquids. ¿ American Geophysical Union 1995