NEW YORK – A privately funded initiative that pays students in some New York City high schools up to $1,000 for passing Advanced Placement tests is not making the grade, critics say.

Students at the 31 schools participating in the program called Rewarding Achievement, or REACH, took 345 more tests this year than last year. But the passing rate dropped slightly, from 35 percent in 2007 to 32 percent this year, according to results released Wednesday.

A total of 1,161 students passed 1,476 Advanced Placement exams, earning $500 each time they scored a 3, the lowest passing mark. They received $750 for each score of 4, and $1,000 for each top score, 5. Nearly $1 million was given to the students and another $500,000 to the participating schools.

Advanced Placement tests are offered in various subjects; students who pass them earn college credits.

The program, launched last fall, is similar to others around the country that aim to boost student achievement through cash incentives.

There are limited studies on the programs' effects, but research by an independent think tank at Stanford University indicated they can raise scores. A separate study examining schools in Ohio also showed score gains after the start of a program that paid students for passing state tests.

Edward Rodriguez, executive director of REACH, called New York's cash-for-scores program a success.

“We are delighted to congratulate the REACH Scholars who earned high marks on rigorous college-level exams,” he said.

But Pedro Noguera, a professor at New York University's Steinhardt School of Culture, Education and Human Development, said he was surprised the test scores didn't jump a bit.

“I would have thought, for kids who were on the borderline, that they would have seen an improvement,” he said.

Schools Chancellor Joel Klein said the program had several successes. More students earned 5's on the tests this year than last, though the number of 4's and 3's dropped, he said.

The program is funded by the Pershing Square Foundation, a charity affiliated with hedge fund Pershing Square Capital Management LP. The initiative is intended to increase the number of poor and minority students who are prepared for college.

“I'd invest in tutoring before I'd invest in incentives,” he said.

David Sanford, who graduated from Benjamin Banneker High School in Brooklyn and received a 3 on the A.P. physics test, said the incentive program was a good idea.

“It helped motivate students to study more and try harder,” he said.