When girls turn into teens and swap baggy sweaters for heels and nail polish, something gets lost. Not the will to live (that comes after the first heartbreak), but the will to read. A typical 10-year-old who can't wait to get hold of the next Roald Dahl or Anne Fine won't go anywhere near a book by the time she is 13.
With so much attention given to reluctant boy readers, it is surprising to find how many girls also eschew books. Thankfully, authors such as Louise Rennison and Cathy Hopkins are starting to change that.
Ms Rennison is now published by HarperCollins but it was a small independent publisher, Piccadilly Press, that spotted her and helped to launch a new kind of series for teen girls. Brenda Gardner, Piccadilly's founder, realised that young teens wanted more than fantasy or issue-led titles to keep them reading. Not all 12 and 13-year-old girls are ready for stories about early pregnancies, soul-searching or drug-taking.
The authors believe that what these girls want to read and talk about isn't necessarily sex (kissing is as far as it goes in this series) but parents, friendships, dating and teen angst. Most of all, says Ms Rennison, they want to talk about themselves.
"They are self-obsessed - they like high drama and suffering," she says.
"When I meet them, they all want advice about their relationships. They treat me like I'm half grown-up and half retarded teenager. But they also want to have a laugh, I think they like the cheeky uselessness of my books."
Brenda Gardner signed up Ms Rennison after reading a column she'd written for London's Evening Standard. "She was very funny and it made me think that we needed a teen Bridget Jones," she says.
Ms Rennison's first draft was called "Daisy's Diary" but Daisy became the irrepressible Georgia, and the first volume of Georgia's confessions was called Angus, Thongs and Full Frontal Snogging.
The success of Angus spawned a number of other teen-diary series, including the Mates, Dates series by Cathy Hopkins (Piccadilly Press). "It's the boy thing," says Ms Hopkins, "that's what girls want to read about. The first date, the first kiss - they want to know what boys want. I mean, how do you know if you're a good kisser? You can get to 40 and still be asking that question."
She says she is yet to hear of a case in which the first kiss went well.
"They'll either be knocking noses or braces," she says. These are not the kind of books that win the big literary awards, but they get teens reading and talking. One young fan, Suzie, discovered Cathy Hopkins and Rosie Rushton when she was 13 after finding her friends giggling at breaktime over the embarrassments of teen life that fill the books' pages. Rosie Rushton's Trials and Tribulations of Five Teenagers series includes the titles, How could you do this to me, Mum? and I think I'll just curl up and die.
Ms Hopkins gets many emails from girls who wouldn't normally read books, but say they've charged straight through eight of her novels. Kathryn, 14, says she'd been turned off reading because all that seemed to be on offer was Harry Potter and Jacqueline Wilson.
"I like these series because nothing majorly depressing happens and the stories are about things I can relate to," she says.
Not all Ms Hopkins' characters are super-cool - indeed, Lucy has the greatest fan base, despite being only five feet tall and flat-chested.
"The rest of her mates are five-foot-seven and look like models while she thinks she still looks like a kid," says the author. "But young people relate to that - they want to know how to get noticed by boys when they're not super-attractive."
Friendship is a preoccupation at this age, too, say Ms Gardner: "Even though girls are often obsessed with boys, all our books subtly point out to girls how important their friends are - that they should not forsake their friends for a boy."
Friendship is also central to all Ms Hopkins' books. "Best friends are a big issue at this age - this is when you can make friends for life," she says. "But it's also when you can become very insecure about friends.
"In my first book, Mates, Dates and Inflatable Bras, Lucy thinks Izzy, who's been her best friend forever, is going to become best friends with the new girl."
In a more recent book, the whole group of girls split up over a boy. "That can be really difficult because you define yourself by your friends," she says. But she makes sure that friendship always wins through.
But there are more serious issues. In the latest offering from Ms Hopkins, Mates, Dates and Great Escapes, a 14-year-old girl is seeing an older boy, being pressured to have sex and saying no.
In Keep Your Hair On*, another recent book from Piccadilly, Elizabeth Vercoe writes about a16-year-old girl who has cancer. She tries to keep her condition hidden from her boyfriend and her friends, before realising it's best to talk things through.
Piccadilly Press isn't the only firm targeting the young teen market. Among others, there's Meg Cabot's The Princess Diaries (Macmillan), although publishers are generally investing more in edgier novels for older teens.
Does it matter if teenage girls don't read for pleasure? Maybe not, but these books have helped their young fans through the early teenage years, and now they are moving on to other kinds of fiction. Kathryn recently read Malorie Blackman's Noughts Crosses - by no means a light read - and Suzie has moved on to fantasy: Sherryl Jordan's Secret Sacrament and Garth Nix's Sabriel. Even so, she hasn't quite lost the taste for the drama of young women's day-to-day lives: she highly recommends Bridget Jones' Diary.
Reviewed in 'TES Teacher' today