Second-hand smoke (SHS; ie, exposure to smoking of friends and spouses in the household) reduces the likelihood of smoking cessation in noncancer populations. We assessed whether SHS is associated with cessation rates in lung cancer survivors. Patients with lung cancer were recruited from Princess Margaret Cancer Centre, Toronto, ON, Canada. Multivariable logistic regression and Cox proportional hazard models evaluated the association of sociodemographics, clinicopathologic variables, and SHS with either smoking cessation or time to quitting. In all, 721 patients completed baseline and follow-up questionnaires with a mean follow-up time of 54 months. Of the 242 current smokers at diagnosis, 136 (56%) had quit 1 year after diagnosis. Exposure to smoking at home (adjusted odds ratio aOR, 6.18; 95% CI, 2.83 to 13.5; P < .001), spousal smoking (aOR, 6.01; 95% CI, 2.63 to 13.8; P < .001), and peer smoking (aOR, 2.49; 95% CI, 1.33 to 4.66; P = .0043) were each associated with decreased rates of cessation. Individuals exposed to smoking in all three settings had the lowest chances of quitting (aOR, 9.57; 95% CI, 2.50 to 36.64; P < .001). Results were similar in time-to-quitting analysis, in which 68% of patients who eventually quit did so within 6 months after cancer diagnosis. Subgroup analysis revealed similar associations across early- and late-stage patients and between sexes. SHS is an important factor associated with smoking cessation in lung cancer survivors of all stages and should be a key consideration when developing smoking cessation programs for patients with lung cancer.