SAN PEDRO, Calif. (AP) _ When Melissa Martinez finishes high school next month, she will leave with a record of straight A's, a college scholarship and memories of times when she was student body vice president and homecoming princess.

But there will be no cap and gown, no ''Pomp and Circumstance.'' Melissa, 17, is six months' pregnant and officials at the Catholic school she attends, Mary Star of Sea in San Pedro, have barred her from the June 6 ceremony.

Some students refused to go to classes Friday when protests by supportive students failed to sway school officials to change their decision.

A crowd estimated at more than 200 gathered outside the school and chanted, ''Lisa, Lisa.''

''She has the support of the whole school,'' one student said.

The girl's father, Joseph Martinez, said his daughter is devastated by the school's decision. ''She made a mistake and she's sorry, but she didn't want to get an abortion,'' Martinez said.

In a statement, high school Principal Carolyn Quijano said it was not the school's intention to punish Melissa, known to her classmates as Lisa.

''The school has tried to show forgiveness and support of Lisa in her decision to carry her baby, but forgiveness and empathy do not mean approval,'' Ms. Quijano said. ''The school made every effort to ensure that her education was not impeded in any way, that she be able to receive scholarships and awards and that she would receive her diploma. This school has not been remiss in its responsibility to her.''

Ms. Quijano added: ''Lisa also has to be responsible for her decision and for the consequences of her decision, and the school must support the teachings of the church. She agreed not to participate in the ceremony as a condition to finish her education.''

Monsignor Patrick Gallagher, pastor at Mary Star of the Sea Catholic Church, declined comment.

Melissa, who has been accepted into a pre-medical program at the University of Southern California, said she plans to keep her baby. She acknowledged that she once agreed with Ms. Quijano that she would not participate in the graduation ceremony.

But she now says she was given no choice. ''They gave me an ultimatum to either leave school or stay and not attend school functions,'' she said, ''but I was really kind of forced because she (Ms. Quijano) knew how much I wanted to stay. It was either say yes or get kicked out.''