Objectives. This study aims to identify the role of self-efficacy, recovery self-efficacy, and preparatory planning with regard to short-term smoking relapse. We also assessed whether the importance of these variables differed for smokers quitting individually and without help (self-quitters) and smokers quitting with the help of a smoking cessation course (group quitters). Design. A longitudinal quasi-experimental study with follow-ups at 1 and 3 months after the quit attempt was conducted in order to assess the role of baseline self-efficacy, recovery self-efficacy, and preparatory planning on short-term relapse. Methods. The recruitment included adult daily smokers (N = 121), quitting in a smoking cessation course (N = 57) and self-quitters (N = 64). Respondents received internet-based questionnaires 2 weeks before quitting (baseline) and 1 and 3 months after the quit attempt. Predictors of relapse were analysed using logistic regression analyses. Results. Relapse at 1 and 3 months after the quit attempt was predicted by low levels of baseline self-efficacy. Simple slope analyses revealed that less preparatory planning significantly predicted relapse at 1 month after the quit attempt among group quitters, but not among self-quitters. Recovery self-efficacy was only predictive of relapse after 1 month when self-efficacy was excluded from the analyses. Moreover, among group quitters, the results indicated a borderline significant curved relation between recovery self-efficacy and relapse after 1 month. Conclusions. Our results suggest that more research is needed on the role of preparatory planning and recovery self-efficacy. Moreover, we recommend incorporating self-efficacy increasing techniques in relapse-prevention interventions.