A Halloween episode percolating this week at the University of Pennsylvania shows how college presidents nowadays, just like politicians, must be constantly on guard for unscripted encounters with cameras. At Penn, the trouble stemmed from an annual costume party for hundreds of students given by Amy Gutmann, the president. At the party, Ms. Gutmann, costumed as a princess, was photographed with a student who had come dressed as an Islamist suicide bomber, complete with fake explosives and a fake automatic rifle.

According to The Daily Pennsylvanian, the student, a senior named Saad Saadi, said it was all a joke, and was understood to be a joke by everyone, including Ms. Gutmann. The president has a different recollection. In a statement posted today on Penn’s Web site, she said she didn’t realize how Mr. Saadi was dressed until after the picture had been taken, and she refused to permit any more to be shot. “The student had the right to wear the costume,” she wrote, “just as I, and others, have a right to criticize his wearing of it.”

There has in fact been plenty of criticism, and in the blogosphere and elsewhere more of it has stuck to Ms. Gutmann than to Mr. Saadi, even though it was the student who had appeared to find fun in terrorism. The IvyGate blog, for example, opined that Ms. Gutmann had not done herself any favors if she really wanted to be the next president of Harvard.

For his part, Mr. Saadi apologized for his choice of costume and denied he was expressing a political agenda with it. On his Web site, he said it was meant to portray a scary character, “much like many other costumes on Halloween.”