Use of smokeless tobacco (moist snuff and chewing tobacco) is a significant public health problem but smokeless tobacco users have few resources to help them quit. Web programs and telephone-based programs (Quitlines) have been shown to be effective for smoking cessation. We evaluate the effectiveness of a Web program, a Quitline, and the combination of the two for smokeless users recruited via the Web.To test whether offering both a Web and Quitline intervention for smokeless tobacco users results in significantly better long-term tobacco abstinence outcomes than offering either intervention alone; to test whether the offer of Web or Quitline results in better outcome than a self-help manual only Control condition; and to report the usage and satisfaction of the interventions when offered alone or combined.Smokeless tobacco users (N= 1,683) wanting to quit were recruited online and randomly offered one of four treatment conditions in a 2×2 design: Web Only, Quitline Only, Web + Quitline, and Control (printed self-help guide). Point-prevalence all tobacco abstinence was assessed at 3- and 6-months post enrollment.69% of participants completed both the 3- and 6-month assessments. There was no significant additive or synergistic effect of combining the two interventions for Complete Case or the more rigorous Intent To Treat (ITT) analyses. Significant simple effects were detected, individually the interventions were more efficacious than the control in achieving repeated 7-day point prevalence all tobacco abstinence: Web (ITT, OR = 1.41, 95% CI = 1.03, 1.94, p = .033) and Quitline (ITT: OR = 1.54, 95% CI = 1.13, 2.11, p = .007). Participants were more likely to complete a Quitline call when offered only the Quitline intervention (OR = 0.71, 95% CI = .054, .093, p = .013), the number of website visits and duration did not differ when offered alone or in combination with Quitline. Rates of program helpfulness (p <.05) and satisfaction (p <.05) were higher for those offered both interventions versus offered only quitline.Combining Web and Quitline interventions did not result in additive or synergistic effects, as have been found for smoking. Both interventions were more effective than a self-help control condition in helping motivated smokeless tobacco users quit tobacco. Intervention usage and satisfaction were related to the amount intervention content offered. Usage of the Quitline intervention decreased when offered in combination, though rates of helpfulness and recommendations were higher when offered in combination.Clinicaltrials.gov NCT00820495; http://clinicaltrials.gov/ct2/show/NCT00820495.