Abstract We assessed potential relations between indicators of indoor dampness and mold exposures at home and the level of asthma control among adults. The present population-based cross-sectional study, the Northern Finnish Asthma Study (NoFAS), included 1995 adult subjects with bronchial asthma who replied to study questionnaires (response rate: 40.4%). The Asthma Control Test (ACT) was used as the measure of asthma control. We calculated the mean difference in ACT score (ACTdifference) and the risk ratio (RR) of poor asthma control (ACT ≤ 19) for the exposure and reference groups and applied Poisson regression to adjust for potential confounding. Exposure to indoor dampness at home was related to a significantly reduced level of asthma control (ACTdifference: −0.83, 95% CI: −1.60 to −0.07), especially among men (ACTdifference: −2.68, 95% CI: −4.00 to −1.37). Water damage (aRR = 1.29, 95% CI: 1.01, 1.65) and indoor dampness, especially among men (aRR = 1.92, 95% CI: 1.15, 3.20), increased the risk of poor asthma control. We provide evidence that exposure to indoor dampness at home reduces asthma control among adults, especially in men. Indoor visible mold and mold odor were not significantly related to asthma control. Advice on how to prevent indoor dampness at home should be an important part of asthma management.