Cognitive susceptibility to smoking is indicated by positive social expectancies about smoking, being curious about smoking, wanting to try smoking, and intending to try smoking. Among children, cognitive susceptibility is a risk factor for initiating smoking; reducing susceptibility is, therefore, a viable primary prevention strategy. Our study tested prospectively the combined effect of two variables-parental modeling of smoking cessation and parental exposure to an antismoking parenting program-on cognitive susceptibility to smoking among children who had never puffed on a cigarette. The study sample comprised 859 daily smokers who called a state Quitline seeking assistance to quit smoking and these adults' 8- to 10-year-old children. The factors in the 2 × 2 design were parental modeling of cessation (successful cessation vs. continued smoking) and parental exposure to an antismoking parenting program (program vs. control). We hypothesized that children whose parents both quit smoking and received the antismoking parenting program would report lower susceptibility to smoking than children exposed to one or neither of these factors. Multivariable analysis of variance, conducted using child-reported susceptibility to smoking collected 12, 24, and 36months post-baseline, confirmed this hypothesis. Post hoc tests for simple main effects showed that, at each time point, parent smoking cessation had a significant protective effect on children's susceptibility to smoking, but only among children whose parents received the parenting program. These tests also showed that the parenting program had a significant protective effect on children's susceptibility to smoking, but only among children whose parents had successfully quit smoking. Our study results suggest that Quitlines and other programs that assist adults in quitting smoking could extend the reach and benefits of such assistance by providing parents with resources that promote antismoking parenting practices.