ObjectivesEnvisioning one's (non)smoking future may make (un)desired future identities more accessible, salient, and personally relevant and facilitate smoking cessation. The current study assessed whether a future-self intervention can weaken smoker self-identity and expected identity loss when quitting smoking, and strengthen quitter- and nonsmoker self-identity, while accounting for personal factors—socioeconomic position, nicotine dependence, consideration of future consequences, and clarity of the envisioned future-self. Additionally, it examined the association between smoking-related identity and quitting intention and behavior. MethodsThis longitudinal online experimental study randomized 233 adult smokers to an intervention condition (where they completed mental imagery, visual, and verbal tasks about a future (non)smoking self), or to a passive control condition. Smoker-, quitter-, nonsmoker self-identity and identity loss were measured post-intervention and after one- and three-months. Quit intention and attempts were measured at baseline and after one month. ResultsThere was a consistent increase in non-smoker self-identity, and decrease in smoker self-identity and identity loss over a period of six months for all participants, but no significant difference in smoking-related identity between the intervention and control group. While personal factors did not moderate the effect of the intervention, we found that smoking-related identity constructs do vary with nicotine dependence, consideration of future consequences, and clarity of the envisioned future-self. Quitting behavior is primarily associated with non-smoker self-identity. ConclusionsAlthough the future-self intervention did not significantly influence smoking-related identity or behavior, identity—in particular, non-smoker self-identity—is important to consider in smoking cessation interventions. More research is needed to find effective operationalizations for identity-based interventions in the context of smoking.