Maryland high school students performed better on Advanced Placement tests for college than students in 45 other states, according to results for the 1997-98 school year.

Seventy-one percent of Maryland students passed, placing the state fourth nationally, tied with Connecticut. Nationwide, the rate was 63 percent. Six counties--Anne Arundel, Baltimore, Carroll, Frederick, Howard and Montgomery--led the way in Maryland, while other jurisdictions--notably Prince George's and Baltimore City--fell below the national average.

"These tests are tough, and while I would certainly like to see each system have equally high pass rates, the most important issue is that more Maryland students are encountering challenging, college-level curriculum and instruction," said Nancy S. Grasmick, the state school superintendent.

Students who pass an Advanced Placement test in a subject receive college credits, enabling them to skip certain course requirements when they reach college. To prepare for the tests, students take Advanced Placement courses in high school, and AP courses have been magnets for high-achieving students.

The courses, prepared by the College Board, of Princeton, N.J., are designed by college professors and are faster-paced than standard high school classes. They also help bolster college applications. In recent years, they have become more like college preparatory courses, where students can get a taste of college-style learning, rather than only courses in which the gifted can excel. That has led to lower scores nationwide, according to Wade Curry, director of Advanced Placement for the College Board.

In Maryland, however, scores have remained steady, even though the number of students taking AP tests has doubled in the last five years.

"I think Maryland's expectations for the performance of students has been set high," said Diane Sprague, coordinator of gifted and talented programs in Anne Arundel County.

Patti Caplan, a spokeswoman for Howard County schools, also attributed the success to high expectations. "It comes from the parents," Caplan said. "It's a culture that starts at home."

Caplan, who grew up in Iowa, said that the educational atmosphere in Maryland is much different. "There is a different level of competition in this state to get into the Ivy League and the good schools," she said.

Baltimore City and Prince George's County had 47 percent pass rates, far below the state average. In rural counties, such as Somerset, Dorchester and Garrett, fewer than 30 students took AP exams. High-scoring counties averaged more than 1,000 test-takers, with Montgomery reaching 3,525. Montgomery also had the highest passing rate, 83 percent.

Determining which students can take an AP course has always been tricky, Curry said. Schools want as many students as possible to be exposed to the rigorous courses, and high participation enhances a school's reputation and may help more students get into better colleges. But the courses can frustrate and discourage students who are not intellectually ready. Restricting AP courses to the gifted has drawbacks as well. In fact, the College Board has been asking schools to open the courses to more students during the last decade. Scott Swail, the board's associate director for policy analysis, said schools will have to figure out how to strike a balance through trial and error.

The AP system was born in the early 1950s, when educators were trying to figure out how to challenge high school seniors, especially those who excelled. Each of the 32 courses is designed by a panel consisting of three college professors, three high school teachers and one academic specialist, who oversees the process.

The courses are updated about every four years to incorporate new material and respond to feedback from top-echelon universities. English literature is the most popular AP course, with U.S. history a close second and calculus third. New courses are designed every few years. The latest entries are environmental science and statistics, the most rapidly expanding AP course. Now being prepared are courses in world history and human geography, a course that is part sociology and part anthropology.