In this paper, the impact of energy-conserving retrofits on air leakage and indoor air quality is assessed for several houses that are part of the weatherization program in the Pacific Northwest and a single home in Cranbury, NJ, that had been weatherized by its owner and later received a house doctor retrofit and a special super-retrofit. Of primary concern is whether or not the air quality indoors is seriously compromised by the implementation of energy conservation measures that reduce air leakage.