A corsage for her, a criminal background check for him.

Cape Cod high school administrators recently ordered background checks on prom dates who were not students, then banned six who had criminal records.

The school eventually relented and allowed the dates to attend. But it was another example of how prom preparations around the country are changing as administrators try to head off trouble on the big night via such measures as age restrictions, alcohol screenings and background checks.

"Proms you always worried about, but there was an innocence to them. Now, kids these days have more brass, they're more sophisticated," said Paul Dakin, school superintendent in the Boston suburb of Revere. The school has an under-21-only rule for promgoers to try to stem the flow of alcohol to minors.

Background checks for dates who aren't students are only one hurdle at West Salem High School in Oregon. All students also must pass by an administrator at the door who "gets pretty up-close and personal," said principal Ed John. If a student appears to have been drinking, a police officer gives a sobriety test.

A plan to give alcohol breath tests at the Hilton Head High prom in South Carolina was scrapped amid legal concerns. Instead, students who wanted to attend last Saturday's prom were required to go to a presentation where parents and students wore goggles that simulated how four drinks can affect motor skills.

At Montclair High in New Jersey, parents and teens must sign pledges before youngsters can buy tickets to the prom. The teens must promise not to drink or use drugs. And parents must give their home and cell numbers and be reachable the whole night.

Dates from outside Montclair High must send in photo IDs with their birthdates and sign the pledge, too. No one over 21 is admitted.

The changes are not without controversy. In Minnesota last month, a 22-year-old Iraq war veteran could not attend the Ada-Borup High prom with his fiancee, a high school senior, because of an under-21 age limit.

Underage drinking and partying have long been associated with proms, as have annual efforts by police and administrators to stem problems. Some schools hold the prom the day before graduation to discourage students from getting blind drunk the night before, or they hold a 6 a.m. after-prom raffle that students must attend to win.

At Dennis-Yarmouth High on Cape Cod, students were required to submit a form signed by themselves, their dates and their guardians. The form gave no indication that non-students would be subjected to criminal background checks. Six people who were found to have records that included drug, alcohol and violent offenses were barred.

The backlash led to a state investigation into whether school officials improperly gained access to crime records.

Last year at Taunton High in Massachusetts, drunken students became unruly and danced on the tables. This year, students must pass a Breathalyzer to enter the prom.

Jacob McPherson, a senior and a member of the school's Students Against Destructive Decisions chapter, said a prom with restrictions is well worth having.

"It's just one last day of seeing the kids we've spent 12 years with, just a time to dance and have a good time," he said.