n a world where sexual orientation is polarized into heterosexuality and homosexuality, bisexuality comes as a disturbing challenge, at once a riddle and a discomfort. "It threatens rigidity," says Lani Kaahumanu, a bisexual activist in San Francisco. "It threatens both sides of the framework." Bisexuals often inspire nervousness, distaste and hostility in both straights and gays and are all but ignored by scholars.

In truth, sexual identity is a complex weave spun of desire, fantasy, conduct and belief; pulling on any one thread distorts the fabric. Even defining one's own sexual orientation can be difficult.

People may be attracted to someone but unwilling to act on their desires out of guilt or shame; conversely, others may act contrary to their true feelings.

Because of society's reluctance to recognize their existence, bisexuals often face an even more torturous struggle than gays in coming to terms with their identity.