It has repeatedly been demonstrated that increased levels of social support are positively associated with a smoker's likelihood of achieving abstinence. It remains unclear, however, what specific support behaviors influence smoking cessation. This study explores the effects of supportive and undermining behaviors experienced by subjects (N = 624) in the context of a romantic/marital relationship on a number of smoking cessation outcomes. The associations of social support behaviors with one-, two-, and three-year abstinence and recycling and making quit attempts at 6, 12, 24, and 34 months were examined. Frequencies of both supportive and undermining behaviors predicted the dependent variables under study. Subjects whose spouses demonstrated fewer undermining behaviors were more likely to be successful continuous abstainers, whereas participants' recycling and making quit attempts seemed to be best predicted by a greater frequency of supportive behaviors. Initial success at cessation might be associated with increased supportive behaviors by a spouse, whereas lower rates of undermining behaviors might be associated with long-term maintenance. Long-term tailored feedback to spouses of smokers wanting to quit might be helpful.