A law adopting statewide high school exams for graduation took effect in Pennsylvania on Saturday, with the goal of ensuring that students leaving high school are prepared for college and the workplace. But critics say the requirement has been so watered down that it is unlikely to have major impact.

The situation in Pennsylvania mirrors what has happened in many of the 26 states that have adopted high school exit exams. As deadlines approached for schools to start making passage of the exams a requirement for graduation, and practice tests indicated that large numbers of students would fail, many states softened standards, delayed the requirement or added alternative paths to a diploma.

People who have studied the exams, which affect two-thirds of the nation's public school students, say they often fall short of officials' ambitious goals.

“;The real pattern in states has been that the standards are lowered so much that the exams end up not benefiting students who pass them while still hurting the students who fail them,”; said John Robert Warren, an expert on exit exams and a professor of sociology at the University of Minnesota-Twin Cities.

“;The exams are just challenging enough to reduce the graduation rate,”; Warren added, “;but not challenging enough to have measurable consequences for how much students learn or for how prepared they are for life after high school.”;

In 2008, state officials in Alabama, Arizona and Washington delayed the start of the exit exam requirement and lowered standards after seeing that many students, including a disproportionate number of minorities, would fail the tests.

Many states have faced lawsuits over the proposed requirements amid accusations that the tests are unfair to students with disabilities, non-native speakers of English and students attending schools with fewer educational resources.

These concerns have been bolstered by recent studies that indicate that the exams lead to increased dropout rates by one or two percentage points, or from 35,000 to 70,000 extra dropouts a year per state.

But proponents say that with the decline in manufacturing and the growth of the information economy, higher educational standards are needed to reinforce the value of a high school diploma. The exams, they argue, give school districts better incentives to succeed and ensure that no one will graduate without documented skills in specific subjects.

“;Momentum is definitely still moving in favor of states' adopting these exit exams,”; said John F. Jennings, the president of the Center on Education Policy, which publishes annual reports on high school exit exams. Jennings added that this momentum was likely to grow next month when the National Governors Association and the Council of Chief State School Officers, which represents state school superintendents, is to release a common core of state standards in English-language arts and mathematics for kindergarten through Grade 12.

Federal officials have set aside $350 million for states to create tests that correspond to the new national standards, and Jennings said there was a good chance that states would consider adopting these new tests for their exit exams.

Despite criticism of exit exams, some experts say that schools have benefited from them. Surveys indicate that teachers say the tests have brought clearer guidelines on curriculum, which they find helpful. And after the exam grades begin to count, students often start taking them more seriously, which causes passage rates to increase, Jennings said.

Gerald L. Zahorchak, the secretary of education in Pennsylvania, is a strong advocate for the state's new tests, which will be phased in over the next five years.

“;I want more than anything to be able to say with confidence that every Pennsylvania student who receives a diploma is ready for the real world,”; Zahorchak said.

He added that in 2007-8, more than 20,000 public high school graduates who enrolled in a public higher education institution required some form of remedial help, with a total cost to taxpayers, students and parents in excess of $26 million.

Nonetheless, responding to fervent opposition from legislators, teachers' unions and advocates for parents who feared a loss of local control, Pennsylvania opted in October to allow school districts to substitute their own versions of the exit exams, with state approval, and to give students who fail multiple times alternative paths to graduation.

The rules in Pennsylvania require students to pass at least four courses, with the end-of-course exams counting for a third of the course grade. If students fail an exam or a section of an exam, they will have two chances to retake it. If they cannot pass after that, they have the option of doing a subject-specific project that is approved by district officials.

The exams are not cheap. Education officials in Pennsylvania estimate it will cost $176 million to develop and administer the tests and model curriculum through 2014-15, and about $31 million to administer each year after that.

Because individual school systems in Pennsylvania can substitute their own exams, state officials and experts do not consider Pennsylvania among the 26 states that have official exit exams.

Twenty-four states now use at least some part of the exams for federal accountability under the No Child Left Behind law, up from just two states in 2002, according to the center.

Eleven states use either a single comprehensive exam, or single exams in math and English, to evaluate what high school students have learned. The other 15 — including Massachusetts, New Jersey, New York and Texas — use end-of-course tests on multiple subjects. This approach tends to face less opposition because the incremental tests can be more easily linked to course content and can be used more directly to increase rigor in coursework.

Also among those states using end-of-course exams is Arkansas, where seventh, eighth or ninth graders will this year for the first time be required to pass the end-of-course Algebra I test to qualify for a diploma.

Critics of Arkansas' system say it fails to show true math proficiency because students have only to score 24 out of 100 to pass the test and those who fail will be granted two additional chances to take the test. After that, they can take a computerized tutorial that is followed by a test.

Tom W. Kimbrell, the commissioner for the Department of Education in Arkansas, rejected that criticism.

“;The alternate options are not some escape valve that everyone gets to use,”; Kimbrell said. “;They are mechanisms that require the student and teachers to go back and actually learn the material.”;

But as deadlines have neared, the opposite concern has led many states to lower or delay their requirements.

In Arizona, lawmakers extended a law in 2008 that was supposed to expire that permitted students who failed the exam to graduate if they met certain grade requirements.

That same year state education officials in Alabama approved an emergency rule allowing students to graduate if they passed just three sections of the exit test, rather than all five, as long as two were math and reading.

Washington lawmakers also eliminated the math section of the final exit exam in 2008 in favor of math exams to be administered at the end of each course.