For the second year in a row, city teachers had a hard time getting tenure. The Department of Education says 55 percent of those eligible for tenure this year won the added job protections.

Teachers are eligible for tenure after three years on the job but because tenured teachers have due process rights, Mayor Michael R. Bloomberg has urged his school administrators to be more selective about which teachers earn tenure. Last year, 58 percent of eligible teachers were granted tenure, a significant drop from 89 percent the previous year.

“Receiving tenure is no longer an automatic right, and our new approach ensures that teachers who are granted tenure have earned it,” said Schools Chancellor Dennis M. Walcott.

This year, about 4000 teachers were eligible for tenure, a decrease from last year because fewer teachers have been hired since 2008. The city says 42 percent of those who were eligible had their probationary period extended by another year, while three percent were denied tenure altogether, meaning they have lost their jobs.

The Bloomberg administration believes that delaying tenure decisions can also help weed out poor quality teachers. Officials said 74 percent of teachers rated as unsatisfactory by their principals got extensions and 23 percent of them were denied. The percentage of outright denials has been steady for years, a sign that few teachers are rated at the very bottom.

New York City isn’t alone in trying to make it harder for teachers to earn tenure. In neighboring New Jersey, Governor Chris Christie signed a law this month that requires teachers to work for four years before being eligible for tenure; they also have to have good reviews.

But it’s too soon to know if efforts like these are paying off with better teachers said Sandi Jacobs, vice president of the National Council on Teacher Quality and a former teacher at Brooklyn’s P.S. 9. “Even two years ago there wasn’t a single state that had connected the awarding of tenure to teacher effectiveness,” she noted.

The president of the United Federation of Teachers, Michael Mulgrew, issued a statement asupporting a rigorous process for granting tenure. However, he said, “If New York City hopes to have a great school system, it will need to come up with better methods of helping teachers develop, not only at the beginning but throughout their careers.”

Mr. Mulgrew pointed to union data finding about 29 percent of the teachers hired for the 2008-2009 school year left the system before they were even eligible for tenure.

Principals now recommend teachers for tenure based on three categories: teacher practice, evidence of student learning and contributions to the school community. They are asked to rate teachers on a four-point scale in each of those areas, ranging from ineffective to highly effective. And they’re supposed to use data from classroom observations and student work in addition to progress on state exams and attendance.

In previous years, principals were given teacher data reports, which calculated the impact of individual teachers on student test scores. But the city no longer generates those reports.

Districts are required to use a new teacher evaluation system that includes student test scores by January of 2013, in order to continue receiving state funds. But the city and the United Federation of Teachers have yet to hammer out the details, even though the governor and the unions agreed on the broad strokes for a framework last winter. The two sides say they continue to talk.

“We must improve the tenure process even further, and a teacher evaluation system will do just that and ensure our teachers are taught by the best,” said Mr. Walcott.

This week the state generated its first batch of data reports for thousands of fourth through eighth grade teachers based on student progress on math and reading tests. These reports were given to school districts to use in their new teacher evaluation systems, whenever they’re up and running.