Since 1999 we have conducted an experimental study of water retention under vapor-dominated conditions. Using samples from semiarid regions of California and Idaho, we are exploring possible correlations of dry-range water retention with more easily measured properties, such as particle sizes and surface area. This work ties in with our theoretical studies of water retention and flow under conditions that approach oven-dryness.The data from this study will also be useful for testing the Rossi-Nimmo (1994, 1996) model using only a few measured retention points.