The purpose of the study was to examine the interaction between parental smoking status and parental attitudes, as measured by positive parental concern, on the risk of adolescent cigarette smoking. Parental smoking and parental concern about smoking were measured in a cross-sectional study of 37,244 students, a random sample of Maryland middle and high school students, who were current or never smokers. Parental concern was classified into 3 levels: strict, moderate, and minimal. The likelihood of youths being current smokers was positively associated with both parental smoking (both versus neither parent smokes: odds ratio [OR] 3.4, 95% confidence interval [CI] 3.1-3.7) and parental concern about smoking (minimal versus strict concern: OR 2.3, 95% CI 2.1-2.4). Youths with parents who did not smoke and with strict concern had the lowest likelihood of smoking. In comparison to this group, after adjustment for other social influences the likelihood of being a current smoker was more than 5 times greater among boys (OR 5.8, 95% CI 4.5-7.4) and girls (OR 5.2, 95% CI 4.1-6.5) whose parents both smoked and were minimally concerned about smoking. Current smoking in youths was independently associated with both parental smoking and less parental concern. When these 2 factors were jointly considered, the prevalence of current smoking in youths increased both with exposure to parental modeling and reduced parental concern about smoking. The results indicate that minimal parental concern about smoking worsens the risk due to parental modeling. Parental modeling and parental attitudes act synergistically to exacerbate the likelihood of smoking.