American girlhood ain't what it used to be. Maybe there are pockets of girls out there who still revel in the Little House on the Prairie books or dress up their dolls or run lemonade stands. But they aren't catching the eyes of sociologists, who seem to agree that girls today are growing up in a hyper-sexualized peer pressure-cooker and they don't show up in Girl Culture, a new book from photographer Lauren Greenfield (Chronicle Books; $40.00). Even the youngest girls in Greenfield's gritty, gorgeous portraits are far too busy dressing up like Barbie dolls to play with them. A gentle warning: this is not a book for parents desperate to maintain their naivete about what's happening in their daughters' lives: these accounts show you more than you've ever imagined about the sexual and social habits of girls. Greenfield's photographs are accompanied by narratives from the girls themselves; the stories they tell, which are unflinchingly raw and honest, are often difficult to read. No matter how well you think you understand what goes on in adolescent life, it can be shocking to read first-hand accounts of the jealousy, pettiness, meanness and general anxiety that characterize female adolescence. The girls in this book range in age from pre-school to post-grad. And Greenfield makes good use of the insecurities of each age, zeroing in on the shame of an 11-year-old at fat camp, emphasizing the anxiety of an up-and-coming actress standing outside her trailer, highlighting the terrible uncertainty of a teenage girl who is banished, by virtue of her rounded face and curly dark hair, from the blonde, slim world of the popular girls. While it will come as no surprise to learn that beauty and appearance feature prominently the minds of most girls, Greenfield's portraits reveal the force with which the need to be desired, even objectified, in a very adult way is expressed, as well as the unexpected ambivalence with which that objectification, once achieved, is