As Congress resumes, we can expect a heated debate as the House and Senate work out differences between their competing immigration reform bills. One of the more contentious issues is whether the law should enshrine English as the national language.

For many, the issue has become so emotional and symbolic that practical benefits — largely for immigrants themselves — have been pushed into the background. That’s a shame. Because regardless of which side prevails in this debate, Congress has a real opportunity to focus the nation’s attention on a far more pressing issue — the importance of learning English.

In terms of immigrant economic success and social well-being, a wide range of studies have shown that learning English is virtually the single most important key to “making it” in America. It is a common source of tension for New Yorkers, or residents of any large city, when language barriers stand in the way in even the simplest acts of commerce.

Regardless of where an immigrant lives, what level of schooling he attains, or how long he has lived in this country, no factor contributes more to his advancement in American society than fluency in English.

Quite simply, for our nation’s newest residents, if you learn English — and the sooner the better — you’re statistically much more likely to have a more prosperous life. In fact, immigrants can raise their earnings by well over 20% if their ability to speak English is raised from “not well” to “very well.” Meanwhile, improving English language skills dramatically narrows the wage gap between recent immigrants and native-born Americans — by 16-18% for males and 6-10% for females.

A study of immigrants in New York City by the Federal Reserve Bank of New York found a strong connection between low levels of English fluency and low median earnings. Foreign-born residents from countries where more than 60% of American immigrants are fluent in English earned nearly twice as much as those from countries where fewer than 40% of American immigrants speak English fluently.

Once an immigrant has been in America for a significant number of years, those who speak English very well earn 67% more than those who speak English poorly.

Among language-minority 18- to 24-year-olds, those who speak English very well are nearly three times more likely to have completed high school than those who do not, and are far more likely to be enrolled in college.

Similarly, employment rates and income are substantially higher among these young adults than among their counterparts whose skills aren’t as strong. And even in ethnic neighborhoods — where exposure to both learning English and hearing about mainstream jobs is often hindered — evidence suggests that the benefits of English fluency are just as strong.

Furthermore, it’s not simply wages that are affected by English language skills. In 2003, a survey by the U.S. Bureau of Labor Statistics found that workplace fatalities were 13% higher for Latinos than for the average worker. And according to a recent study of immigrant families in Los Angeles and New York City, about half of families headed by adults who spoke no English experienced food insecurity.

One hundred years ago, America adopted an English language requirement for the nation’s newest immigrants when Congress passed a bill mandating that “no alien shall hereafter be naturalized or admitted as a citizen of the United States who can not speak the English language.” In 1950, Congress strengthened the law by stipulating that America’s newest citizens had to read and write the language as well.

As Congress returns from recess, lawmakers will consider whether they should strengthen the law once again by making English the nation’s official tongue.

It is as essential now as ever before that we strive to assimilate our immigrants and their children into a unified America — with command of English, knowledge of our national heritage, and the tools to ensure they can contribute within their community.

The best way for immigrants to achieve the American dream is to learn English — regardless of whether it’s our official language or not.

Mr. Soifer is executive vice president of the Lexington Institute, which is based near Washington, D.C.