Objective: Smokers who are not motivated to quit are an important group for intervention, particularly if they have children with asthma. Research indicates that unmotivated smokers are less responsive to intensive interventions, although motivation-by-treatment interactions have not been tested. This study examines whether motivation to quit moderates the effect of a cessation induction intervention. Method: Parents had an asthmatic child requiring urgent care, and did not have to want to quit smoking to be eligible for the study. Two home visits included asthma education, motivational interviewing (MI) for cessation, and feedback on child’s secondhand smoke exposure (SHSe). Participants were then randomized (n = 339, 79.6% female) to receive Enhanced-PAM (Precaution Adoption Model; 6 MI calls including SHSe feedback) or PAM (6 contact control calls). Motivation to quit was assessed at baseline and point-prevalence abstinence (ppa) and SHSe outcomes were objectively measured. Results: At baseline, 38.9% were not motivated to quit. Those who were not motivated to quit were 3 to 4 times more likely to be abstinent at 6 months in Enhanced-PAM versus PAM (7-day ppa: OR = 3.71, 95% CI = [1.06, 12.99]; 30-day: OR = 4.15, 95% CI [1.20, 14.35]); those receiving Enhanced-PAM achieved quit rates comparable to motivated smokers. Those who were not motivated to quit were more than 4 times as likely to have very low/undetectable SHSe at follow-up in Enhanced-PAM versus PAM (OR = 4.46, 95% CI [1.31, 15.15]). Among motivated smokers, neither outcome significantly differed by treatment arm. Conclusion: It cannot be assumed that smokers who are unmotivated to quit will not be responsive to intensive interventions.