The average American college graduate's literacy in English declined significantly over the past decade, according to results of a nationwide test released yesterday.

The National Assessment of Adult Literacy, given in 2003 by the Department of Education, is the nation's most important test of how well adult Americans can read.

The test also found steep declines in the English literacy of Hispanics in the United States, and significant increases among blacks and Asians.

When the test was last administered, in 1992, 40 percent of the nation's college graduates scored at the proficient level, meaning that they were able to read lengthy, complex English texts and draw complicated inferences. But on the 2003 test, only 31 percent of the graduates demonstrated those high-level skills. There were 26.4 million college graduates.