Growth in the market for electronic cigarettes (e-cigarettes) raises complex questions about the devices' public health implications and, hence, challenging policy issues. We propose a policy agenda addressing concerns about preventing youth uptake of e-cigarettes and the desire to realize the potential of e-cigarettes to increase adult cigarette smoking cessation. We organize interventions according to the "four Ps" of marketing: product, price, place, and promotion. Policies include decreasing the addictiveness of combusted tobacco products while ensuring the availability of consumer-acceptable reduced-risk nicotine products, imposing large taxes on combustible products and smaller taxes on e-cigarettes, limiting the sale of all tobacco and (nonmedicinal) nicotine products to adult-only retailers, and developing communications that accurately portray e-cigarettes' risks to youth and benefits for inveterate adult smokers. All members of the public health community should unite to pursue a shared commitment to the principle that both youth and adults deserve a future free of tobacco-related disease.