The history of tobacco control policy is marked by both successes and failures. While taxes, regulations, and various behavioral and pharmacological interventions have helped many people quit smoking, they have not helped everyone. These strategies are unlikely to contribute greatly to smoking cessation among the remaining group, and intensifying these strategies risks backfire. Conversely, using e-cigarettes (vaping) relieves nicotine cravings while avoiding harmful cigarette smoke. And yet, rather than reporting the growing evidence that e-cigarettes provide an off-ramp from smoking for many nicotine-dependent adults, the public discourse on e-cigarettes more often emphasizes e-cigarette use by young people, prompting fears about nicotine dependence and e-cigarette use leading to smoking. A critical review of the available evidence concerning the health effects of vaping and whether the use of e-cigarettes helps or hinders smoking cessation does not fully resolve the polarization in the discourse. Disagreement persists about how the available evidence should be produced, reported, and interpreted. These volumes address these points in a succinct and clear manner. Across all three volumes, the authors highlight the important normative questions that remain unresolved by detailing unexamined assumptions. The books enable readers to reconsider what constitutes "harm," how much risk is acceptable, and which social groups should be prioritized. Highlighting that the net impact of e-cigarettes on public health is not immutable but rather hinges upon the regulatory environment, the books examine the opportunities and challenges of optimizing e-cigarette regulation. The authors analyze controversial policies designed to discourage vaping and whether these nudge consumers toward or away from riskier alternatives. Drawing on economics, policy analysis, and regulatory science, the authors adopt a social welfare-based approach to explore how regulation can balance the risk and benefits of e-cigarettes to help divert current and future generations from smoking-related harms, while discouraging the use of e-cigarettes by nonsmokers.