South Philadelphia High faces a radical restructuring in the fall, after this afternoon's announcement that the school has been formally designated as a "Renaissance School."

That designation triggers changes in how the school operates and who works there, and comes after years of poor academic performance.

Today, Philadelphia School District officials announced the full list of 18 Renaissance Schools, which will be reconstituted in September, either as charters or district schools.

Teachers at South Philadelphia High who declined to be identified by name said they were notified by letter today - triggering wide uncertainty and some tears.

The letter, signed by Superintendent Arlene Ackerman, said, "Your school will remain a neighborhood school and all current students will continue to attend." It also warned, "This designation may effect your employment status with the district."

In certain kinds of Renaissance schools, at least 50 percent of the teaching staff must be replaced. Administrators too may have to leave.

South Philadelphia High was designated a "Promise Innovation" school, which places no limit on the percentage of current staff that can be retained. Theoretically, every teacher could go, or every one could stay.

New principal Otis Hackney declined to comment when reached by phone today.

Under the Promise Innovation guidelines, he would remain in his job.

The model also requires that teachers work an additional hour during three days of the week, and that staff work a longer school year to include summer academy. Additional support staff are to flow to Promise Innovation schools in the form of a parent ombudsman, student advisor, nurse and resource specialist - several of which are already in place at Southern.

South Philadelphia High, known as Southern, drew national attention last school year, when 30 Asian students were attacked by groups of mostly African American classmates. That and other incidents triggered state and federal investigations, ultimately resulting in a legal settlement that mandated new rules, interventions and training.

The school made strides this year under Hackney, who instituted a raft of new policies and procedures aimed at increasing cultural understanding.

Hackney learned of the new designation only this morning, according to people who spoke with him, and was focused on how teachers would handle the news.

Hackney took over in September amid what had become a revolving door in the principal's office, gaining support from teachers, community advocates and students who believe things were finally improving.

The Renaissance School designation "is extremely alarming," said Helen Gym, a board member at Asian Americans United, which pushed for reform at Southern. "Why the district would refuse to take action last year when that school was in crisis, and now that we've started to stabilize the school, they throw it into upheaval again. I think this community deserves some serious answers."

Academics at Southern have been dismal. Last year, only 14 percent of students could read at grade level and 18 percent could do math at grade level.

Renaissance Schools are chosen on the basis of historic academic performance.