Editor's note: Rachel Simmons is co-founder of Girls Leadership Institute and author of "The Curse of the Good Girl: Raising Authentic Girls with Courage and Confidence." Follow her on Twitter: @Racheljsimmons
(CNN) -- Spring may be graduation season, but the most coveted rite of passage for many teenage girls is the prom.
From the latest craze of "promposals" to the minute-by-minute social media broadcast of it all, the rituals of prom form a throwback cultural primer called "How to be a young woman." Teen girls are competing relentlessly to be queen.
The queens of prom are the conventionally beautiful, the wealthy and the heterosexual -- always passively waiting to be asked.
Isn't prom just a fun dance that hardworking students deserve? Sure, but it's also an event where girls internalize damaging cultural messages. Those who are exalted on this "once in a lifetime" night offer an object lesson in how modern girls are expected to look and act.
Prom is a cultural report card of sorts on how well, or not, young women are doing.
Here's what a bright 17-year-old girl learns as her lace gown drags behind her into the school gymnasium:
She learns that she must have money to attend the prom
Prom was modeled after the debutante ball of the old days, where elite girls formally announced they were ready to date, while a hand-picked bevy of suitors watched. Today, prom is still a rich girl's party.
In 2013, prom spending will rise on the shoulders of a more robust economy. Families who plan to spend money on the big night are expected to drop an average of $1,139. All that cash might be good for business, but it disadvantages the poor and working class girls who can't keep up. Meanwhile, boys can get away with renting a tux for less than $100.
She learns that conventional beauty is valued above all else
Girls will spend lavishly on expensive dresses and shoes, along with professional tanning, hair and makeup. The final look is a far cry from Molly Ringwald's original, homespun vibe in the '80s teen classic "Pretty in Pink."
Instead, girls are angling for the Hollywood red carpet look. Oscar gown knockoffs, such as a copy of Jennifer Lawrence's pink Dior dress, are among the most sought after this season.
Prom drops girls squarely into the beauty spending pipeline. It prepares them to shell out a disproportionate amount of money on their appearance as adult women, when they will spend $7 billion annually on makeup alone.
She learns that the most valued girls must wait to be asked
Asking season can begin during the winter, consigning girls looking for a date to months of anxious waiting. Nor is it enough just to be invited; now, the truly successful prom girls get elaborate public promposals, with suitors spelling out "Prom?" in cupcakes or smoke, as was the case with the boy who hired a skywriter.
By contrast, the brave girls who do the inviting often endure a scrim of embarrassment for breaking the unwritten rules. The message?
Assertiveness makes you less attractive, a lesson girls are likely to draw on as women, when they avoid asking for raises and are seen as less likeable when they do.
She learns to broadcast every minute of it to get 'likes'
Prom culture is now painstakingly documented on sites such as Instagram and Facebook, exacerbating the angst of the uninvited.
The near constant posting of photos -- of having one's hair done, doing makeup, riding in the limo -- becomes a strategic social press conference, announcing to anyone with a social media account that you are playing the game. The online photo albums are anxiously monitored as barometers of popularity, telling girls who is "in" and "out," as many girls learn to equate their worth with the number of "likes" each photo receives.
The underside of this constant self-promotion is comparing oneself endlessly to others. The prom beauty contest in girlhood is a final dress rehearsal for modern womanhood when, in one study, 80% of women said they competed with peers over appearance.
She learns that straight is better
Who you bring to the prom is under as much scrutiny as the hem of your dress.
In all but the most progressive communities, prom glorifies heterosexuality, leaving gay youths facing disapproval at best, outright rejection at worst.
In its 2011 School Climate report, the Gay Lesbian and Straight Education Network found that same-sex couples were frequently not allowed to attend school dances together or were penalized for doing so, such as being ineligible for "couple discounts" on tickets.
The good news is that the rules of prom are starting to change.
Girls are pushing back against the pressure to wait for an invitation and are asking boys first. Lindsay, 17, a senior from San Antonio, engineered her own promposal with a poem, a special T-shirt and poster.
Meanwhile, same-sex couples are growing more visible. Dates are being replaced by whole groups of friends attending together. This spring, girls in Georgia used social media to end their town's racially segregated proms with national support.
When I went to prom in the early 1990s, I seesawed between my wish to get asked by the right guy and ride in the cool kids' limousine with the burgeoning realization that I was gay. I had a fun night, but I was far from my authentic, assertive self that night. Prom felt mostly like a job I had to do to maintain my position in the social hierarchy.
Three decades after Title IX, our culture has yet to decide how powerful it wants its girls to be. As we figure out the answer, prom becomes an even more important cultural touchstone for who we want our girls to become.
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The opinions expressed in this commentary are solely those of Rachel Simmons.