The discussion is specific to single-family homes (detached houses), as opposed to apartment buildings, other multiple family dwellings, or office and other public use buildings. Introductory information covers indoor radon sources, health effects of radon exposure, radon level monitoring methods, and a discussion on how radon enters and builds up in house air. Covered are nine methods for reducing indoor radon in detached houses: natural and forced-air ventilation, forced-air ventilation with heat recovery, active avoidance of house depressurization, sealing major radon sources, sealing radon entry routes, drain-tile soil ventilation, active ventilation of hollow-block basement walls, and sub-slab ventilation. For each method, information is presented on principles of operation, applicability, how much confidence one can have that the method can achieve radon reduction, and an estimate of installation costs. Where appropriate, drawings depict the details of method installation using terminology familiar to the building trades.