EPA’s Indoor Environments Division commissioned an Exploratory Study of Basement Moisture During Operation of ASD Radon Control Systems, under a cooperative agreement with Auburn University, Auburn, Alabama. The principal investigator was Brad Turk of Environmental Building Sciences, Inc., Las Vegas, New Mexico. The purpose of the study was to better understand the potential moisture reduction benefits from the operation of residential radon control systems. The report contains information of interest to a wide variety of audiences. Therefore, EPA is making this contractor’s report publicly available. Because it is a contractor’s report, its findings, conclusions and recommendations are those of its authors, not necessarily those of EPA. The Agency believes that this information may be useful to industry associations, standard-setting organizations, government agencies and consumers.