INTRODUCTION:Text-messaging programs for smoking cessation, while efficacious, have high dropout rates. To address this problem, we developed and tested the feasibility and early efficacy of a peer-mentoring intervention for smoking cessation provided by former smokers. METHODS:Adult US smokers were recruited nationally into a randomized pilot trial (N = 200), comparing 6-8 weeks of automated text-messaging support (SmokefreeTXT) and automated text support plus personalized texts from a peer mentor who formerly smoked. The primary outcome was biochemically verified 7-day point-prevalence abstinence at 3 months post-quit date, assessed on an intention-to-treat basis (missing = smoking). Self-reported abstinence, program acceptability, user engagement, and user perceptions were also assessed. RESULTS:Biochemically verified abstinence at 3 months was 7.9% (8/101) in the intervention group and 3.0% (3/99) in the control group (adjusted difference 6.5, 95% CI = 0.7% to 12.3%; p = .03). Self-reported abstinence at 3 months was 23.8% (24/101) in the intervention group versus 13.1% (13/99) in the control group (adjusted difference 12.7, 95% CI = 1.2% to 24.1%; p = .03). The intervention had a positive but insignificant effect on overall satisfaction (78.3% vs. 72.9% control group, p = .55). Having a mentor did not significantly alter duration of interaction with the program nor the proportion unsubscribing, although the intervention group reset their quit date with greater frequency (p < .01) and sent more messages (p < .01). CONCLUSIONS:Peer mentoring combined with automated text messages was feasible and acceptable and increased smoking abstinence compared with automated messages alone. The results highlight the promise of this intervention approach and the need for a full-scale evaluation. IMPLICATIONS:Providing quitting assistance by automated text messaging has been shown to increase smoking abstinence. Yet, dropout rates in text-messaging programs are high. No studies have tested the effectiveness of peer mentors who are former smokers as part of a text-messaging intervention, although they represent a promising way to retain, engage, and support smokers. This randomized pilot trial suggests that peer mentors can complement automated text-messaging programs to promote smoking abstinence.