SACRAMENTO - California students who are still learning English are taking too long to master their new language, which puts them at risk of falling behind in math and reading and hampering their education, according to a report released Thursday.

An analysis of two years of results from the California English Language Development Test found that only half of English learners are making significant gains, said a report by the Legislative Analyst's Office.

Students in second and third grades are faring especially poorly, the researchers said.

Using the 2001 and 2002 test results, LAO researchers project that about half of kindergarten students would become proficient in English by sixth grade. Another 30 percent of the initial group would become fluent in the next three years.

But, the projection estimated that 40,000 students who enroll in California schools after kindergarten won't become fluent by the time they graduate, said LAO researcher Paul Warren, the author of the report.

The data "suggest the transition to English fluency is taking too long," Warren said in the report.

Students who are "still learning English in grades 4, 5 and 6 risk falling behind in academic proficiency and failing to master the skills needed for success in middle and high school," the report said.

About 1.3 million students took the test in 2001 and about 1 million took it in 2002. The largest share -- about 83 percent -- of those students speak Spanish.

A student who scores 4 or 5 on the annual test could be classified as fluent, while a score of 1 indicates a beginning level of English.

In 2002, about 37 percent of English learners scored a 3 on the annual test, which means they are not yet fluent, but have a "high level of proficiency," Warren said in the report.

About 450,000 students, or 35 percent, scored 4 or 5, and about 375,000 scored either 1 or 2 in 2002.

Warren found that more than 70 percent of students who scored a 1 in 2001 jumped to a 2 the next year. About 64 percent of students who scored a 2 in 2001 also moved up one level the following year, he said.

The gains slow for the students who scored 3 or higher on the test, with less than half of the level 3 students progressing a level the next year, and only 22 percent of level 4 students scoring a 5.

Researchers noted that the tiny subset of students who speak Mandarin, about .6 percent of those taking the test, master English faster than others.