Of all the ways that governments can try to help people, cash transfers can seem like one of the most straightforward. Their popularity has been growing: Over the past decade, dozens of American cities have launched cash-transfer pilots. During the coronavirus pandemic, governments worldwide dramatically expanded their own programs’ reach. And as AI reshapes work, the idea of guaranteed income—a specific kind of recurring, no-strings-attached cash payment—is moving into the mainstream. Yet while the provision of cash has saved many lives in dozens of low- and middle-income countries, it has seemingly produced only modest health gains in the United States. Guaranteed-income pilots also haven’t delivered the dramatic health improvements associated with cash-transfer programs elsewhere. Why does cash save lives in Tanzania but barely move the needle in Texas?From our work studying cash-transfer programs across 37 countries, we’ve come to see a consistent logic behind why cash succeeds in some places and falls short in others. Cash transforms health when four particular conditions are met. Most U.S. cash-transfer pilots have lacked them. But one major American policy does come close: the federal food-assistance program SNAP. Its success offers a road map for what effective cash assistance can look like in this country, if we choose to build on it.###First among the necessary conditions, cash infusions must be large enough to change one’s daily reality. In many low-income countries, a modest amount, on the order of $20 a month or less, can represent a major share of household income. For families living in extreme scarcity, a small influx of funds can expand their food budget, allow children to get vaccinated, or help a mother reach a hospital to deliver safely. These changes are big enough to save lives.In the U.S., by contrast, a few hundred dollars a month for a relatively short period of time, typical of guaranteed-income pilots, rarely matches the steep costs of housing, child care, and health care. The support modestly eases financial instability but doesn’t fundamentally alter the constraints that low-income families face.Second, cash must be able to remove specific barriers that block good health. In the countries we studied, many of the leading causes of death—HIV, tuberculosis, malaria, malnutrition—are tightly linked to poverty. Families face life-threatening obstacles that a small amount of money can help them overcome, by creating access to transportation, better nutrition, a skilled birth attendant. When families have a little more income, the health effects can be immediate and profound.In the U.S., the dominant health problems are chronic diseases shaped by neighborhood environments, structural inequities in housing and health care, and years of accumulated risk from unhealthy diets and other long-term exposures. These problems are far less responsive to short-term financial boosts. Cash can reduce stress and improve stability, but it cannot, on its own, undo the deep roots of these conditions. Yet in certain periods of life—such as during and after pregnancy—cash can have an immediate impact because health outcomes hinge on whether people can meet their basic needs and show up for health care when it matters most.Third, scale matters. Successful cash-transfer programs reach large portions of the population. When millions of people receive support, the benefits spread beyond individual households, which helps explain why such programs have reduced mortality across entire countries. U.S. pilots have been small, reaching only hundreds or thousands of families—too limited to change the broader conditions that shape health outcomes.Finally, cash works best when it is woven into social infrastructure that families already rely on. In many low- and middle-income countries, payments are linked with health visits and other essential services. Brazil’s Bolsa Família program, for instance, operates alongside an extensive primary-care system and has been credited with preventing hundreds of thousands of deaths. In the U.S., cash-transfer studies and guaranteed-income pilots are typically disconnected from other programs that translate cash into health gains.These conditions help put common criticisms of such programs in perspective. Fears that cash discourages work or fuels spending on alcohol or drugs have not held up in the research. Across rich and poor countries, cash transfers have minimal or positive effects on work and do not increase drinking, smoking, and other substance use.##Although many U.S. pilots have fallen short, SNAP is the one American program that comes closest to the global success stories. Its payments are large enough to meaningfully reduce poverty. The program targets a barrier, food security, directly tied to health and survival. It reaches more than 40 million people. And it is administered through state systems that connect it, albeit imperfectly, with other public systems, including Medicaid and school meals. It is no coincidence that SNAP is the only U.S. income-support program convincingly linked to improved survival. In many ways, it resembles the global cash-transfer programs that have delivered the largest health gains.Although SNAP benefits currently remain too small to eliminate food insecurity for many households, expansions during the Great Recession and the pandemic demonstrated that larger benefits and smoother access can make the program far more effective. SNAP’s impact is greater when benefits are adequate and when eligible households can easily stay enrolled. Instead of incorporating these lessons, changes in the One Big Beautiful Bill Act move in the opposite direction—tightening eligibility and cutting funding in ways that could mean millions lose their benefits. (The Trump administration has justified these cuts in part by arguing SNAP is rife with fraud and abuse. Fraud does occur, as it does in any large federal program. But by the government’s own estimations, this represents a small fraction of SNAP spending, and the large majority of the tens of billions of dollars the U.S. spends on the program benefit Americans.)SNAP is not the only instructive example. The U.S.’s earned-income tax credit can also deliver a sizable cash benefit, typically as a lump sum, that low- and moderate-income workers can use to catch up on bills, pay down debt, or cover necessities. Because it is built into the tax-filing process, it avoids eligibility churn and can be readily expanded by states. It’s not a health program, but past expansions have been linked to improved child health. The Special Supplemental Nutrition Program for Women, Infants, and Children, or WIC, is much smaller than SNAP in scope and generosity, but it’s integrated with local clinics and pairs food support with nutrition counseling and care referrals for pregnant and postpartum women, as well as infants and young children. By increasing access to healthy foods during a crucial period, and freeing up money that would otherwise go to groceries, WIC has been linked to improved birth outcomes and infant health.Smaller programs can also have a clear impact if they are designed to meet the four conditions. Rx Kids, launched in Flint, Michigan, in 2024, offers cash transfers to parents and infants and closely follows the global playbook: It has a meaningful transfer size, near-universal reach within the city, benefits that target pregnancy and infancy, and links to the health system. Early evaluations of the program suggest substantial improvements in birth outcomes. The political will for such an approach at the federal level may not exist, but Flint shows what local efforts can achieve when the conditions are right. Michigan’s recent decision to invest hundreds of millions of dollars to expand Rx Kids statewide, enough to reach roughly one-third of all births, suggests a plausible U.S. path to scale.Although these programs require public investment, the returns can be high. For young children, SNAP delivers roughly $60 in benefits for every dollar spent. The question is not whether cash is misused, but whether we choose to structure programs at the size and under the conditions where cash does the most good. Cash is not a cure-all. But when designed with the right basic ingredients, cash transfers are one of the most powerful levers that governments have to alleviate poverty and improve health.