There are three noteworthy elements in this new research. First, the benefits often are not captured by short-term outcomes like improvements in children’s test scores, which typically last only a few years before fading.

Second, while program design certainly matters — and can matter a lot — much of the benefit appears to derive from helping low-income families pay for basic needs like food, housing or health care, or simply reducing the intense economic pressure they face. This relates to findings that poverty may increase intense stress, inhibiting young children’s cognitive development.

Third, in many cases, the additional tax revenue from the higher long-run earnings generated by the program is sufficient to repay much or even more than all of the initial cost.

In addition to long-term benefits, the safety net, of course, supports many Americans right now. In 2013, income and nutrition assistance programs lifted 46 million people, including 10 million children, out of poverty, while health programs benefited tens of millions more. As a result, the proportions of Americans who are poor and uninsured have fallen over the past several decades.

Moreover, safety-net programs do not discourage work in any big way. Instead, the E.I.T.C. rewards low-income parents for working. And child care and pre-K programs make it easier for parents to work in the first place, while also putting children in a better position to succeed.

President Obama’s goal is greater mobility and higher incomes. We know that the large cuts to nutrition assistance, health care, housing vouchers and other programs contained in the recent congressional budget resolution would not only hurt the poor today but also shortchange our economy’s future. In contrast, the evidence strongly supports making child care and preschool available to all families with young children, restoring housing vouchers that were cut during the sequester and expanding tax credits for working families.

We cannot solve poverty or lack of mobility overnight, but contrary to what the skeptics say, investing in families works — not just for them, but for all of us.