Why do millions of Americans struggle with reading and writing?

For the first time, a detailed portrait of America's least literate adults is emerging.

About 30 million people – 14 percent of the US population 16 and older – have trouble with basic reading and writing. Correlating factors that were explored in a new government report include poverty, ethnicity, native language background, and disabilities.

Of these 30 million people, 7 million are considered "nonliterate" in English because their reading abilities are so low. When shown the label for an over-the-counter drug, for instance, many in this subgroup cannot read the word "adult" or a sentence explaining what to do in the event of an overdose.

Adult literacy "is a core social issue that if we could fix as a nation, we would make inroads into fixing many other social problems," says David Harvey, president and CEO of ProLiteracy, an advocacy group based in Syracuse, N.Y. "Low literacy levels are correlated with higher rates of crime, problems with navigating the healthcare system, problems with financial literacy. We know that some of the folks who signed subprime mortgages didn't understand what they were signing."

In the coming months, Congress is expected to retool and reauthorize the Workforce Investment Act (WIA), which includes a section to help fund adult literacy and basic education programs. Funding has steadily decreased in recent years, Mr. Harvey says. Since the original WIA in 1998, "we've had a radical change in the economy," he adds. "These folks who are on the lowest ends of the literacy scales are the first to lose their jobs.... Employers now require a higher level of reading, writing, math, and technology skills in order to do low-skilled jobs in America."

The government report, which was released Wednesday, looks at specific skills such as oral fluency (the ability to read out loud quickly and accurately) and decoding (the ability to break apart unfamiliar words and sound them out). It presents new analyses from a nationally representative survey conducted in 2003 by the US Department of Education's National Center for Education Statistics (NCES).

A main goal of the report is to shed light on the extent to which people's low-level reading is due to lack of basic skills such as decoding or to lack of vocabulary or comprehension. The findings suggest that a lack of basic reading skills is a key problem, says Sheida White, a project officer at NCES. "Teachers of adult basic education and other practitioners may [need to] provide diagnostic assessments to adults to see if they could benefit from explicit and systematic instruction in decoding and oral fluency," she said in a conference call with reporters Wednesday.

Oral fluency is scored by the number of words read accurately per minute in word lists and longer passages. The average score among the general adult population is 98. By contrast, among the 30 million who have problems with basic literacy, 49 percent score below 60. Among the 7 million considered nonliterate, the average score is 34.

As part of the government's study, people in the group of 7 million were given an alternative assessment: Interviewers asked them to read individual words or sentences they pointed to on everyday items. The interviewers could speak in Spanish to those who preferred it, but answers had to be given in English. The study treads in relatively new territory by interviewing people who primarily speak Spanish and getting more detail about their English literacy.

In this lowest-level, alternative-assessment group:

•Language background clearly plays a role. Among those who spoke only English before starting school, 39 percent score below 60 in oral fluency. But among those who spoke Spanish before starting school, the percentage of slow readers is much higher: 72 percent.

•Income and education are also correlated with literacy. People below the poverty line account for 58 percent of this group. Most have not obtained a high school diploma or GED.

•Thirty-five percent of the English speakers and 12 percent of the Spanish speakers have disabilities (in categories such as learning, vision, and hearing).

Many community-based organizations that help adults learn English and improve their literacy report long waiting lists for their services. Yet there's still a stigma that makes some adults afraid to ask for help, says Harvey of ProLiteracy. "We need anti-stigma campaigns like those in the public-health field," he says. He also urges a better continuum of local services so that when people do come forward, they don't get "bounced around."