They began as a hip-hop band that tried to keep their music fun, basing their sound on the records made before Gangsta Rap. They developed a loyal following, but didn't have big commercial success until they added Fergie and made their songs more radio-friendly.
The members come from stable backgrounds and have no desire to sing about gangs and violence.
Break dancers used to perform at their concerts. When they hit it big, the dancing and visuals became much more elaborate, as a few guys spinning on their heads wouldn't cut it anymore.
Fergie's real name is Stacy Ferguson. When she was young, she was on a show called Kids Incorporated, about a bunch of kids in a band.
Taboo's real name is Jamie Gomez and he is Mexican American. Apl.de.Ap's real name is Allan Pineda Lindo and he is Filipino. (thanks, Karen - Waterford, Ireland)
Will.i.am's real name is William Adams (formally known as will.1.x, his real name is William James Adams jr.). He hosted a show on MTV2 and started his own clothing line called I.Am clothing. He's a Jamaican and the producer and lead rapper of the band. He met Apl.de.ap in Tribal Nation, a breakdancing crew, in his early twenties. Together, they recruited Taboo to be the third member of the Black Eyed Peas. Fergie joined the group later in 2003's Elephunk. (thanks, Raven - Millville, UT)
Before Fergie joined, Kim Hill was in the Black Eyed Peas as a female vocalist. (thanks, Joseph - Staten Island, NY)
Apl moved to America when he was 14, and quickly became best friends with will.i.am. After forming Tribal Nation, they started a Hip-Hop group known as ATBAN Klan, which stands for "A Tribe Beyond A Nation.
Their first album Grass Roots was not released because their producer Eazy-E died of AIDS in 1995. They were then signed to A&M Records. (thanks, mollie - Philly, PA, for above 2)