Catalyzing smoking behavior change among people unready or unmotivated to quit smoking (PUQS) has the potential to disrupt decades of smoking and toxicant exposure, drastically reducing smoking-attributable morbidity and mortality. Unfortunately, current smoking cessation treatment approaches are typically designed for people who are seeking treatment and ready to quit smoking, which is the minority of people who smoke. Harm reduction product sampling, an extension of medication sampling, is a pragmatic and scalable approach to proactively engage people in transitioning away from combustible cigarette smoking. Sampling does not rely on sufficient motivation to initiate smoking behavior change. Rather, targeting behaviors consistent with quitting smoking (e.g., use of a starter regimen) can fuel motivation and smoking behavior change. In the only harm reduction sampling study to date, we found that a 4-week supply of e-cigarettes produced significant changes in smoking behavior compared to a no-provision control condition. E-cigarette uptake was robust compared to studies of medication sampling where no use or underuse of smoking cessation medication hindered sustained abstinence. These findings, coupled with our recent research, highlighted that any single harm-reduction product is only reinforcing to a fraction of users, but reinforcing value is one of the most important predictors of transitioning away from combustible cigarettes. As such, offering a choice among products is critical to provide appealing options for people with differing preferences and fully test the public health benefits of harm-reduction sampling among PUQS. Three potential alternatives to combusted cigarettes - e-cigarettes (ECIGS), heated tobacco products (IQOS), and oral nicotine pouches (ONPs) - each have the potential to reach more people who smoke than smoking cessation medication, resulting in a greater population reduction in harm from combustible tobacco. We propose the first investigation of harm-reduction sampling versus medicinal nicotine sampling on PUQS smoking behavior, mechanisms of sampling's effects, and potential moderators of these effects. A national sample of PUQS (n= 472, defined as not being ready to quit in the next 30 days) will be recruited and randomized 2:1 to choose one of three harm-reduction products (ECIG, IQOS, ONPs) versus a medicinal nicotine control condition (nicotine patch + lozenge, NPL). Product choice among those randomized to harm reduction will be informed by trying each product after biochemically confirmed overnight smoking abstinence, allowing each participant to try individual products before selecting their preferred option. Upon product selection (or assignment to NPL), participants will receive a 4-week starter product regimen. The primary outcome measure is a biochemically verified 7-day point prevalence smoking abstinence at the 6-month follow- up, with a 3-month follow-up as a secondary endpoint. Secondary outcomes include a 24-hour quit attempt and a 50% cigarette reduction per day. The findings have the potential to fill a critical clinical gap, advance evidence- based harm reduction approaches, and reduce smoking-attributable morbidity and mortality.