They clip our lawns, fix our roofs, deliver our meals, and serve us in restaurants and grocery stores; they endure backbreaking work, out of sight, to make our lives more comfortable; they are trusted to help raise our children. They are the undocumented living in America.

We usually take their work for granted, and we don’t often think of them as parents of U.S. citizens. Now, new research shows a powerful reason for bringing parents without papers out of the shadows — to improve their citizen children’s potential to support our economy. Yet current policies are driving undocumented parents of citizens into hiding — and harming our nation’s economic future.

National data show that immigrants and their children contributed half of the nation’s population growth over the past 20 years. As the baby boomer generation retires, we need to maximize the development of all children — and the more than four million citizen children of undocumented parents are a sizeable group.

Among young children under age six of undocumented parents, an overwhelming 91 percent are citizens. My recent study of the first years of life of hundreds of newborns of Dominican, Mexican, Chinese, and African American parents shows that the key building block of later success – early language and cognitive development – is threatened by virtue of having parents without papers.

Here’s why. Undocumented parents in our study fear signing up their citizen children for services and programs that they qualify for and that would help their early development. These children were born years after their parents had been working in the United States, contributing to our economy, their communities and our society.

Almost all were stable, two-parent families with high levels of employment. These parents expressed the same goals as families across America—to raise children to become productive citizens who make their parents proud and their country strong.

The hardships that undocumented parents experience due to their status can have lifelong consequences for their children. By age two, the children of undocumented parents in our study experienced lower levels of language and cognitive development than did the children of documented parents. Because the foundations of brain architecture are built early, slower language development leads to lower school readiness, which leads to higher school dropout rates.

In the absence of federal action, current policies and proposed legislation threaten millions of citizen children. In Alabama, Georgia, and South Carolina, legislation to allow the police to stop and detain those they suspect of not having papers, modeled on Arizona’s year-old policy, is poised to become law. The deportation of parents thwarts the potential of their citizen children to grow up and contribute to the economy.

Given the proven economic returns from quality early learning centers and preschools, these policies would harm all of our nation’s children. But education is not only an imperative for children. Many studies show the benefits for children of increasing the educational levels of parents in poverty, yet current laws prohibit undocumented parents from accessing such job training and education.

The four million citizen children of undocumented parents are a potential engine for our economic recovery. They have the same rights to pursue happiness and productivity, to fulfill their educational and economic potential. It is time that we consider them assets for our country’s future, rather than second-class citizens.