"It would end the U.S. as we currently know it."

That's Robert Rector of The Heritage Foundation, speaking of what would happen if an immigration proposal by Sens. Mel Martinez (R-Fla.) and Chuck Hagel (R-Neb.) becomes law. Their plan would grant amnesty to 9 million to 10 million illegal immigrants and put those immigrants on a path to citizenship.

Moreover, the Martinez-Hagel plan would pave the way for an estimated 103 million persons to legally immigrate to the U.S. over the next 20 years -- fully one-third of the current population of the United States. Current law allows 19 million legal immigrants over the next 20 years. The Martinez-Hagel plan would add an extra 84 million legal immigrants to that number.

"Effectively, within 20 years, a quarter of the U.S. population will be foreign born" under Martinez-Hagel, Rector says. He calls the prospect of such a huge influx "utterly unprecedented."

If Martinez-Hagel becomes law, Rector says, we can expect "the largest expansion of the welfare state in 35 years."

Why? Consider a few facts Mr. Rector has exposed:

• Half of all adult illegal immigrants lack a high-school degree. Among Latin American and Mexican immigrants, 60 percent lack a high-school degree and only 7 percent have a college degree. By contrast, among native-born U.S. workers, only 6 percent have failed to complete high school and nearly a third have a college degree.
• Immigrant households are about 50 percent more likely to use welfare than native-born households.
• Immigrants without a high-school degree (both lawful and unlawful) are two-and-a-half times more likely to use welfare than native-born individuals.

T hen there's the problem of out-of-wedlock childbearing, which a) correlates strongly with welfare use and b) is more prevalent among foreign-born Hispanics than among non-Hispanic whites (42.3 percent vs. 23.4 percent). "Children born and raised outside of marriage are seven times more likely to live in poverty than children born and raised by married couples," Rector writes. "Children born out-of-wedlock are also more likely to be on welfare, to have lower educational achievement, to have emotional problems, to abuse drugs and alcohol, and to become involved in crime."

Beyond the economic concerns of immigration are security problems. Mixed in with those who simply want to make a better life for their families are some dangerous people. When immigration laws are flouted routinely, terrorists and drug traffickers find it easier to engage in criminal activities. What's needed, James Carafano suggests in another Heritage paper on immigration, is for policymakers to enforce laws that bar employers from hiring illegal aliens.

"Research by the Government Accountability Office (GAO) and the SSA Inspector General suggests an alarming degree of collusion between illegal workers and employers who intentionally turn a blind eye to hiring individuals who are unlawfully present in the United States," Carafano writes. "This collusion helps to fuel a burgeoning population of undocumented workers and encourages unprecedented levels of illegal border crossings."

To reduce those crossings, we need a smarter way to secure our borders, Carafano says in a separate Heritage paper. We need "enhanced and secured infrastructure, appropriate screening, inspection of high-risk cargo and people, persistent surveillance, actionable intelligence and responsive interdic­tion," he writes. "Combining these instruments into effective border security requires not just integrating assets at the border, but also linking them to all activities involved in cross-border travel and transport, from issuing visas, passports, and overseas purchase orders to internal investigations and the detention and removal of unlawful persons."

Do these concerns mean that Americans should shun immigrants? Certainly not. Ours is a country born of immigrants. But immigration reform is long overdue and must emphasize work incentives, not welfare incentives; keep current US citizens safe from terrorists and thugs who enter under the dark of night; and include measures to make sure those legally entering our country are willing to contribute to society and become U.S. citizens. Patriotic assimilation is crucial, as Matt Spalding explains in a paper for Heritage's First Principles Series. "The American theory of citizenship necessitates that the words immigration and assimilation be linked in our political lexicon and closely connected in terms of public policy: Where there is one, there must be the other." Spalding points out that assimilation must include an emphasis on acquiring English, learning about our history, political principles, civic culture and establishing primary allegiance to the United States.

If we do not enact wise reform measures that protect our American way of life, there may one day be no recognizable American way of life left to protect.

Rebecca Hagelin is a vice president of The Heritage Foundation and the author of Home Invasion: Protecting Your Family in a Culture that's Gone Stark Raving Mad.