A school in the US has defended itself after being slammed for body-shaming.
There are still two months until the dance, but Boylan Catholic High School in Illinois has already released a 21-page set of strict prom dress rules.
The guidelines, which say some dresses are ok on certain body types but not others, has prompted a call for a student-run prom.
The school told Newsbeat the rule-book is to teach students moral values like modesty.
In other words: No cleavage and don't flash too much flesh.
Boylan's President Amy Ott says: "Parents tell us the dance dress code is very helpful in guiding them when shopping with their children and picking out something that is both elegant and appropriate.
"As a private Catholic high school, we adhere to teaching our students moral values which include modesty.
"We want all students to feel beautiful in what they wear while also adhering to our values as a Catholic school."
Much of the online controversy is about one specific line in the handbook.
"Some girls may wear the same dress, but due to body types, one dress may be acceptable while the other is not."
This is being seen as body-shaming, and has prompted former pupils to speak out.
The school president went on to say: "We're surprised this story has gotten so much coverage.
"I think it's indicative of the struggle we have as a society in what our young people are encouraged to wear or not wear. They see images on TV and in mass media of what they think is the norm, not what is often appropriate for their age or for a school event. "
But the handbook comes with a warning that any student who ignores the dress code won't be allowed to go to the dance.
It says: "Having been specifically forewarned, we expect nothing less than full co-operation from students and their parents on this issue."
The girls are also told that they can't just stick a shawl on over skimpy outfits.
"No cover-ups (coats, shawls, sweaters) will be allowed over dresses that do not meet dress code."
And for the boys? They barely get a mention.
Just these four pictures to guide them.