Some princesses arrive by magic carriage. Some, though, have to drive themselves, squeezing their hoop skirts into a small sedan and freshening up with the rearview mirror. And some have to carry their gowns down a city block and change in the doorman’s office before arriving at the birthday party, where they will dote on the guest of honor.

Once the door opens, however, the magic begins, and there is absolutely no hint that this princess, clad in a floor-length satin gown with impeccable curls, got here by any means other than a shiny carriage or flying carpet. For the next hour or so, she leads the birthday party guests in singing, dancing and face-painting, regaling them with stories of princess life and teaching them proper princess-like manners. Right before the cake or presents, she slips away, and the children are left aglow with the memory of having been in the presence of fairy tale royalty.

Parents spend billions of dollars each year in pursuit of the perfect birthday parties for their children. Amid that cacophony of clowns, cake and super-sweet sixteens is the enterprise of birthday party princesses: costumed young women — and occasionally, men as princes — who bring a touch of magic and pink tulle into the living rooms of little girls. The demand for party princesses has given rise to an industry that was thrust into the spotlight in September when graphic novelist Mary Alice LeGrow began posting her unusual “princessing” experiences on Something Awful, an online forum, which was then picked up by Huffington Post and NPR.

Many young women work for small companies that were started by party princesses who expanded their staffs as their businesses grew. Maria Aparo, a 27-year-old actress, moved to New York three years ago and cold-called party entertainment companies to find a gig to supplement her income. She joined New York Princess Party as its first additional employee, later partnering with founder Erin Shaw; now their company employs 12 princesses on a part-time basis. Recruiting hasn’t been a problem, as they receive a few emails every month from young women inquiring about a position, much as she initially did. “Since we hire professional actresses, we keep the rotation pretty fresh,” Aparo said. “It’s pretty common for someone to get booked for a national tour and be gone for six months.”

The birthday parties mostly cater to the 5-year-old set, young enough to still be awed in the presence of a flesh-and-blood princess. Party packages can run hundreds of dollars and can include anything from a formal tea service to horse-and-carriage rides. While the business can be lucrative, but most employees have other jobs as well because birthday parties only occur on weekends.New York Princess Parties, for example, books about 10 to 15 gigs a month, though Aparo said the market this fall has been more “erratic” than previous years, perhaps due to the economy and elections. Her princesses are paid $75 an hour plus tips, which usually range from 10-20 percent. It’s not enough to cover a full-time salary unless, perhaps, an entrepreneur ventures into princess schools, such as Little Princess Academy.

There’s always the overhead to consider: princess dresses, most of which must be custom-made, can cost up to $600, not to mention wigs, transportation and goodie bags — plastic tiaras can really add up. Joanna Kovacs, who runs the one-woman Party With A Princess in upstate New York, spent all of the profits from her first year of princessing on new costumes and wigs, and she also works as an online art dealer.

Getting dressed like a princess is one part of the job; more difficult is acting like a “real” princess. Birthday party princesses must stay in character, which can mean driving in complete royal regalia — thus providing much entertainment to other drivers — and parking down the street so as not to be seen exiting a car instead of a carriage. Albany-based Kovacs has stopped by gas station and Dunkin’ Donuts bathrooms in full costume more than once. “Everyone just turns around that looks at you like you’re crazy because it’s not Halloween,” she said. “That’s the most embarrassing part of the job.”

Being in character means smiling 100 percent of the time, sticking to that sing-song, high-pitched voice, and no bathroom or refreshment breaks. Strange questions from children (“Rapunzel, do you want to see my underwear?”) are fielded with eyelash fluttering and a cheerful change of topic, or as LeGrow describes it, “*sparklesparkle*.” City princesses haul all their supplies to the party location and change in a pre-arranged, discrete spot, which can be a neighbor’s apartment or an upstairs bathroom, where they will shed their costumes after the party.

On one occasion as the visit was ending, one of Aparo’s princesses was followed upstairs by the birthday girl, who then caught Snow White in a state of undress. The confused child had to be whisked away by her mother before too many questions were asked. In terms of wrecking the illusion, “kids bursting in and seeing something is probably the most common,” Aparo said.

The princess’ grand entrance results in either hyperactive joy or shell-shocked immobility from the attendees. “Their small brains are trying to compute having a character in their house,” Aparo recounted. “You can see them working it out in their heads.” From there, any number of familiar activities can follow, from animal balloons to the princess version of duck-duck-goose (AKA princess-princess-queen).

At parties with boys and girls, it’s common for some boys to develop on-the-spot crushes on the princess, and they’ll try hardest to win the games. Prince (or pirate) accompaniments are sometimes requested to accommodate the boys, but Kovacs acknowledged that boys have just as much fun with a princess as long as she gives a great performance. The main priority, in any case, is to ensure the happiness of the birthday girl, whether she’s a gurgling infant or worldly 9-year-old.

However, doing the job isn’t as easy as putting on a wig and giving hugs to adoring little girls. Add 10 excited children, and princess duties become a veritable workout. “Kids that age play on the floor and run around, so we really get down there with them,” Aparo said. There’s always the danger of one kid or older sibling who is intent on spoiling the fun for others with his or her disbelief; princesses must be armed with comebacks in the face of “You’re not a real princess” taunts. Successful tactics range from counter-attacks (“That’s a nasty thing to say! I don’t tell you you’re not real!”) to the occasional guilt trip (“This is a special day for your sister, and you want her to be happy, right?”) to simply changing the topic. The majority of the time, though, party attendees are eager to believe that the princess they’ve only seen on TV has materialized in their midst.

Sometimes, awkward situations come not from the kids but from adults. An enamored uncle or father might quietly ask the princess if she also does bachelor parties. Once when Kovacs, as the Little Mermaid, went to the kitchen for a cup of water, a grandfather offered her $200 to “come over to my house and sit in the bathtub.” Astonished, Kovacs replied, “You’d better behave yourself, or I’m definitely not gonna come to your birthday party!”

While many parents participate in the activities or stick around to film the event, some relegate the princess to babysitter status and go off to drink wine on the patio with the other adults. This has actually happened to LeGrow, who pointedly noted that that being hired as an entertainer and nanny are two different jobs. The distinction is also clearly stated in contracts that New York Party Princess makes with parents. “Our entertainers will not reprimand your children, so parents know that this isn’t a situation when someone shows up for an hour and they can just leave,” Aparo said. Nevertheless, the princess must be accommodating in hopes of receiving a generous tip at the end of the party.

Apart from payment, some companies also request that parents must keep the house at a relatively low temperature, as the hoops, fabric and corsetry of princess costumes are rather stifling. To help with wrangling party guests, princesses sometimes bring along a hostess or “royal maid” whose responsibility is to set up the next game and ensure smooth transitions.

With Disney’s continual expansion of their princess cast, the idolization of princesses in American culture doesn’t seem to be abating. Princess worship has been portrayed negatively, such as in Peggy Orenstein’s book “Cinderella Ate My Daughter.” Orenstein criticizes princess culture for promoting rigid gender roles and consumerism, and indeed, a child’s obsession with tiaras and fairy godmothers can unnerve many parents. Party princesses take a softer view of the princess-mania phase that besets young girls; many of them can identify with the childhood love of dress-up and sparkly things. “It’s just the idea of being special and being admired,” Aparo said. “It has to speak to girls on some level of make-believe and wanting to be grown-ups.”

And just as girls eventually outgrow the fairy tale phase, birthday party princesses also have to retire from their roles. At 31, LeGrow is more than a decade older than some of her company’s new hires, and she’s working off of her youthful looks while she can. Having been a princess for the past four years, Kovacs, 30, expects to continue for at least five more before passing the crown, so to speak. For now, the money is good, and the emotional rewards are many as well, even for Aparo, who didn’t expect to like the job as much as she does. “It’s kind of what you always wanted to do as a kid anyway, but now you get to make money doing it as an adult.”