A 15-year-old girl is incarcerated in a Chicago mental hospital in 1981 and kept there for three years because she won't wear a dress. A Winn-Dixie truck driver is fired from a job he held for twenty years when his boss learns that he wears women's clothes at home. A small-time hustler in Falls City, Nebraska, is raped and then murdered when he's discovered to be physically female. A woman bleeds to death after a Washington, DC, hit-and-run accident when, after finding male genitals under her clothes, paramedics stand by laughing.

M or F? For most of us that's a simple question, decided while we were in utero. Checking off that box–at the doctor's, on the census, on a driver's license–takes scarcely a thought. But there's an emerging movement of increasingly vocal people whose bodies or behavior unsettle that clear division. They're calling themselves "transgendered": It's a spongy neologism that, at its broadest, absorbs everyone from medically reassigned transsexuals to cross-dressing men to women so masculine that security guards are called to eject them from women's restrooms. Fellow travelers include intersexuals (once called hermaphrodites), whose bodies are both/and rather than either/or. The slash between M/F cuts painfully through these lives.

And so they've started to organize. Brought together by the Internet, inspired by the successes of the gay rights movement, and with national sympathy gained from the movie Boys Don't Cry, intersex and transgender activists are starting to get a hearing in organizations ranging from college campuses to city councils, from lesbian and gay rights groups to pediatric conferences. And, like the feminist and gay rights movements before them, the new sex-and-gender activists may force us to rethink, in life and in law, how we define and interpret the basics of sex.

A first clue to how zealously the M/F border is guarded–to how sex is literally constructed–comes at birth. One in 2,000 infants is born with genitalia ambiguous enough to make doctors hem and haw when parents ask that first question: boy or girl? Since the late 1950s/early 1960s, standard medical procedure has been to lie and obfuscate. Rather than explain that the child is "a mixture of male and female," writes Anne Fausto-Sterling, author of Sexing the Body, medical manuals advise physicians to reassign the child surgically to one sex or another, telling parents only that "the gonads were incompletely developed…and therefore required removal." A large clitoris may be cut down; a micropenis may be removed and a vagina built; a testis or testes are sliced out–sometimes over the parents' explicit objections.

Now some of those children have come of age and are telling their stories: severe depression, sexual numbness and a longtime despair at having been folded, spindled and mutilated. The leader of this nascent movement is Cheryl Chase, who in 1993 organized the Intersex Society of North America. ISNA opposes reassignment surgery on intersex infants and advocates raising intersex children as social males or females, educating them about their bodies and letting them choose at puberty whether they'd like surgical assistance or a shift in social sex. ISNA's cause was helped when Johns Hopkins sex researcher and PhD John Money, who wrote the intersex silence-and-reassignment protocol, was profoundly discredited. After a child he called "John" was accidentally castrated soon after birth, Money advised his parents to have him undergo surgery to construct a vagina, raise him as "Joan" and give him female hormones at puberty. Money reported this involuntary sex reassignment as fully successful. But in 1997, both a medical journal report and a Rolling Stone article revealed that the reassignment had been a disaster. Despite the insistence of parents, doctors, psychologists and teachers, "Joan" had always insisted that she was "just a boy with long hair in girl's clothes." In adolescence, John took back his manhood.

How did John "know" he was male–and by extension, how do any of us decide we're girls or boys? One theory is that, in utero, John had undergone the androgen bath that turns an undifferentiated fetus–which otherwise becomes female–male, giving him a male identity and masculine behavior. In the other rare cases where XY infants lose penises and are raised as girls, some insist on being boys–but others happily identify as (masculine, lesbian) women, which suggests that things aren't quite so simple. Scientists recognize that our brains and nervous systems are somewhat plastic, developing in response to environmental stimuli. Sexuality–all of it, from identity to presentation to sexual orientation–is no exception; it develops as a biological interaction between inborn capacities and outside influences. As a result, most of us have a narrow range in which we feel "natural" as we gender ourselves daily through clothes, stance, stride, tone. For most, that gendered behavior is consonant with biological sex: Girls present as female, if not feminine, and fall in love with boys; boys present as male or masculine and fall in love with girls. But those in whom gendered behavior is vice versa–feminine boys, highly masculine girls–get treated as unnatural, even though their gendering is just as biological as the rest of ours. What happens to these transgendered folks can be so brutal that the pediatric surgeons who cut off infant clitorises or penises look like merely the advance guard of the M/F border patrol.

Take, for instance, Daphne Scholinski, so masculine that at age 6, strangers chastised her when she tried to use women's restrooms. In her dry, pitiless memoir The Last Time I Wore a Dress, Scholinski tells the story of being committed to a mental hospital at 15 for some very real problems, including severe neglect, her father's violence and her own delinquency. The hospital ignored her shocking childhood and instead "treated" her masculinity. Scholinski got demerits if she didn't wear makeup. She was put on a boys' ward, where she was twice raped, to encourage her to be more feminine. Her confinement was so disturbing that she still gets posttraumatic stress flashbacks, including nightmares so terrifying that she wakes up and vomits. And so Scholinski is starting an organization dedicated to reforming the diagnosis of childhood GID, or gender identity disorder, under which she was treated.

Or consider the treatment of Darlene Jespersen and Peter Oiler. After working for Harrah's Reno casino for eighteen years, in the summer of 2000, Jespersen was fired from her bartending job when Harrah's launched a new policy requiring all its female employees to wear foundation, powder, eyeliner, lipstick and so on. "I tried it," says Jespersen in a plaintive voice, "but I felt so naked." The obverse happened to Peter Oiler, a weathered, middle-aged man with large aviator glasses, a pleasant drawl and a bit of an overbite. After twenty years of being rotated through progressively more responsible jobs in Winn-Dixie's shipping yards, in 1999 Oiler was driving a fifty-foot truck delivering grocery supplies throughout southeastern Louisiana–until Winn-Dixie learned that he called himself "transgendered." Oiler tried to explain that he simply wore women's clothes on the weekends: He wasn't going to become a woman; he didn't want to wear makeup and heels on company time. In January 2000 Oiler was fired.

Jespersen and Oiler are stunned. Jespersen is suing Harrah's. Says Oiler, "I was raised to believe that if you do an honest day's work, you'll get an honest day's pay." The ACLU Lesbian and Gay Rights Project has taken up his case, in part because of the sheer injustice–and in part to get courts to treat discrimination against people who violate sex stereotypes as illegal sex discrimination. If a woman can wear a dress, or if a man can refuse makeup, why not vice versa? In doing so, the ACLU, like the three national lesbian and gay legal organizations, would be building on the 1989 Supreme Court decision Price Waterhouse v. Ann Hopkins. Price Waterhouse had told Hopkins that she wasn't going to make partner because she was too masculine–and, in actual written memos, advised her to wear jewelry and makeup, to go to charm school, to be less aggressive. The Supreme Court declared such stereotyping to be sex discrimination.

Will judges see Peter Oiler's dismissal as illegal sex stereotyping? There have been some recent hints that they might. In Massachusetts, for instance, the US Court of Appeals for the First Circuit said Lucas Rosa could sue a bank that instructed feminine Rosa, who had shown up to apply for a loan wearing a dress, to go home and come back in men's clothes; a female, after all, would have been considered for the loan. Another Massachusetts judge said that a male student could come to school in a dress, since female students could. A Washington transsexual prisoner raped by a prison guard, and two New York municipal employees harassed for being gay, were allowed to sue when judges ruled they'd been attacked for violating stereotyped expectations of their sex.

Our society has learned to see why women would want masculine privileges like playing soccer and serving on the Supreme Court, but there's been no matching force expanding the world for males. Boys and men still patrol each other's masculinity with a Glengarry Glen Ross level of ridicule and violence that can seem, to women, nearly surreal. Those males who violate the M-box's limits on behavior are quite literally risking their lives.

Which means that, if you're a performing drag queen, a cross-dressing straight man like Peter Oiler, or a transsexual who still has some male ID, do not under any circumstances get stopped by a cop. In New York City, says Pauline Park, a co-founder of NYAGRA (New York Association for Gender Rights Advocacy), even if the police don't actually beat you, "you could be arrested and detained for days or weeks. They don't let people out until they plead guilty to prostitution. They put them in the men's cell, where they're often assaulted and sometimes raped, as a tactic to get people to plead guilty."

And don't turn to emergency medical personnel. In August 1995 Tyra Hunter's car crashed in Washington, DC. When firefighting paramedics cut away her dress and found male genitals, they laughed and mocked her. She bled to death in the hospital. In August 2000 a jury awarded Hunter's mother $1.75 million in a wrongful-death action. Hunter's experience, unfortunately, is not unusual. Once a month, someone transgendered is murdered, and those are just the documented cases. Transgender activists are beginning to mark November 28, the anniversary of another such death, as a Day of Remembrance, with candlelight vigils and a determination to slow the steady drumbeat of murder.

"We're despised. We're pariahs in this society," says Miranda Stevens-Miller, chair of the transgender rights organization It's Time, Illinois, about transsexuals and otherwise transgendered people. Many transsexuals are fired once they begin to transition. Others lose custody and visitation rights, houses, leases. Many are shut out of office and other public restrooms for years–an indignity that cuts to the very core of being human, since every living body needs to pee. And so the most urgent transgender organizing is happening locally, in organizations such as TGNet Arizona, NYAGRA and It's Time, Oregon. They're teaching Trans 101 to local employers, doctors, city councils, lesbian and gay organizations, judges, families, landlords, friends. They're attempting to collect statistics on firings, beatings, murders, bathroom harassment, police abuse. Often these groups are driven by the energy and determination of one or two people who spend their own time and pennies writing and photocopying leaflets, giving workshops for corporate and college groups, and lobbying city councils and lesbian and gay organizations for inclusion in hate-crimes and antidiscrimination laws. Lately, they're having remarkable success at adding "gender identity and expression" to the protected categories in local and state employment nondiscrimination and hate-crimes laws; they've won in locales ranging from Portland, Oregon, to DeKalb, Illinois, to the state of Rhode Island.

Nationally, trans groups are still in the skirmishing phase faced by any new movement, with the inevitable splits over strategy and personality. The group with the most name recognition, GenderPAC, angers some transgender activists by avoiding the "T" word in its advocacy, saying that it aims at gender freedom for everyone; it acts on behalf of such people as Darlene Jespersen and Peter Oiler, or boys called "faggot" for not being noticeably masculine. Currently the most significant transgender organizations nationally are IFGE (International Foundation for Gender Education), GEA (Gender Education and Advocacy) and the Working Group on Trans Equality, a loose network of grassroots trans activists aiming at a coordinated national presence. Perhaps the biggest success so far is that all the major lesbian and gay organizations and many smaller ones have added transgendered folks to their mission statements as folks who are equally, if differently, queer.

Or is it so different? All of us deviate from what's expected from our sex. While the relationship between transgender activists and lesbian and gay groups has at times been contentious, some lesbian and gay activists, notably Chai Feldblum, Georgetown law professor, are starting to urge that we all organize around our common deviance from sex stereotypes. The differences between homosexual, transgender and transsexual experiences are not that great: All are natural variations on the brain's gendered development that have cropped up throughout human history, from Tiresias to Radclyffe Hall, from Billy Tipton to Quentin Crisp. For the most part, the mainstream sees us on one sliding scale of queerness. And occasionally our struggles and goals intersect quite neatly. For instance, homos can't always tell whether we're harassed at work because someone figures out that we date others of the same sex, or simply because we're too butch or too fey.

And none of us can rely on having our marriages recognized by the institutions around us when we need them–because marriage is one of the last laws on the books that discriminate based on sex. Recently, Joe Gardiner asked a Kansas court to invalidate his dead father's marriage to transwoman (born male, medically and legally reassigned as female) J'Noel Gardiner, saying J'Noel was "really" a man–and therefore could not have legally married a man. The lower court agreed with the son that XY = man, which meant the son would inherit his father's fat estate. But the Kansas appeals judge remanded the case back down for a new trial. Sex, the appeals court declared, isn't decided simply by a chromosome test. Rather, sex is a complex constellation of characteristics that includes not only chromosomes but also "gonadal sex, internal morphologic sex, external morphologic sex, hormonal sex, phenotypic sex, assigned sex and gender of rearing, and sexual identity." The court approvingly quoted Johns Hopkins researcher and medical doctor William Reiner, who wrote, "The organ that appears to be critical to psychosexual development and adaptation is not the external genitalia, but the brain."