The paper discusses EPA experience in monitoring radon reduction in Clinton, NJ, houses. Both the temperature-driven stack effect and typical household appliances (e.g., furnaces, whole-house fans, clothes dryers, and bathroom fans) were observed to reduce indoor pressure and potentially increase radon levels. Radon measurements obtained during cold weather, after residential heating systems were back in full operation, showed that the radon reduction techniques that were applied had been effective and that radon concentrations were significantly reduced. Although both grab sample and continuous monitor measurements were helpful in assessing radon entry sites and hour-to-hour fluctuations, respectively, only charcoal canister data collected under near-winter conditions could be used as a valid comparison with earlier March/April 1986 generated pre-radon reduction data.