In February, Daniel Baldwin--the second-oldest and least well-known of the four Baldwin brothers--overdosed on crack and was arrested in New York's Plaza Hotel. Before getting hauled off by police, he ran naked through the hotel's halls screaming, "Baldwin!" A month ago, Kim Basinger, wife of eldest Baldwin brother Alec, won the Best Supporting Actress Oscar for her role in L.A. Confidential. Last week Alec's new action movie, Mercury Rising, opened to tepid reviews. Which Baldwin is which? How did all four brothers become actors? How are they alike? How are they distinguishable?

First, a quick review of the Baldwin oeuvre. Alec (age 40) claims the greatest screen success. His critical hits include a lead performance, opposite Sean Connery, in The Hunt for Red October (1990). Last year, he starred with Anthony Hopkins in David Mamet's The Edge. Daniel (37) is derisively referred to as the "TV Baldwin." Aside from bit parts in B movies, his only major role was as Detective Beau Felton in NBC's acclaimed Homicide: Life on the Street. Hollywood always touts 35-year-old William (or Billy, as he abhors being called in the press) as the Baldwin most likely to break through to major stardom. But he has done little since his box office hits Backdraft (1991) and Sliver (1993). Stephen (31) remains consigned mainly to teen flicks (though he won acclaim for his supporting role in The Usual Suspects). Textbook example: the 1996 comedy Bio-Dome, where he plays opposite ex-MTV star Pauly Shore.

(There are two Baldwin sisters: Jane [32], a physical therapist in Syracuse, N.Y., and Beth [42], a Long Island housewife. Both say they will never take up acting.)

Profiles chalk up the brothers' success to 1) good looks and 2) on-screen intensity. The Baldwins say they inherited both from their handsome, demanding father, Alexander, a devoutly Catholic social studies teacher from Massapequa, N.Y. (Alexander died in 1983, and the brothers claim still to be driven by their devotion to him.) Because they are Irish-Catholic, tightknit, and play touch football, the Baldwins constantly compare themselves to the Kennedys. It is a Baldwin commonplace to say that either Alec or Billy will become president. The Baldwin matriarch, Carol, sometimes refers to herself in interviews as Rose.

Had the Baldwin patriarch lived longer, many speculate, the brothers wouldn't have taken up acting. According to this theory, Alexander was adamant that they become lawyers, and his objections would have stymied their careers. However, Hollywood proved irresistible. While a student at New York University, Alec was spotted by a talent scout and offered a spot on the soap opera The Doctors. Stephen claims he has always been a thespian, performing in regional theater and singing with the Long Island Philharmonic. But his acting career took off only when an agent spotted him working in a Manhattan pizza parlor. Billy and Daniel say they both got into acting after they saw how easy it was for their brothers to make it.

Is there a Baldwinian essence? If so, what are its dimensions?

1 The Baldwin Look. Many note similarities in their sinuous, full lips; dimpled chins; and "intense eyes." Profiles also dwell on the Baldwin mane. All but Stephen, who wears a bowl cut, are known to slick back their hair with vast amounts of gel and mousse. (Famous story: It once took two days to shoot a 30 second scene of Billy driving a convertible. Afraid his hair would get out of place, he stopped every few yards to get regelled.) But there are differences too--for example, body hair. The Los Angeles Times noted that Alec has chest hair "like a gorilla." Meanwhile, Billy has a decorative tuft on his chest, Stephen is baby-smooth, and Daniel has yet to take off his clothes on-screen.

2The Stanislavskian Baldwin. All the Baldwins claim to have been schooled in Method acting, studying under teachers with Russian-sounding names. Alec especially worships Marlon Brando, quoting incessantly from On the Waterfront and playing Stanley Kowalski in the Broadway revival of A Streetcar Named Desire. Film critics like to gripe that none of the Baldwins has any range: They're character actors with leading-man bodies. (Each has a niche: Alec is the ideal psychopathic villain, Daniel the hard-drinking cop, Billy the slimy pretty boy, Stephen the screwball comedian.) Several studio executives have jokingly responded that if their talents were combined in a single actor, he would be the next Cary Grant.

3 The Baldwin as Crusader. Alec has been the most outspoken politically. Touted as a potential Democratic senatorial candidate in New York, he was the main attraction of a bus tour in the Northeast, promoting campaign finance reform. He has also lobbied for funding for the arts. Alec makes news with his caustic condemnations: He called Newt Gingrich "evil" and Alfonse D'Amato "the bozo pool attendant from Island Park." After graduating from the State University of New York at Binghamton, Billy interned for Congressman Tom Downey. Both Billy and Alec have headed the liberal actors' advocacy group the Creative Coalition. Stephen and Daniel are apolitical.

4 The Baldwin Bad Boy. With Daniel's arrest, tabloids have dredged up the long history of Baldwins run amok. Only Billy has a reputation as a straight arrow. Most famously, Alec was arrested--and later acquitted--for allegedly punching a paparazzo and spraying shaving cream on the photographer's car windows. On the set, he is known for his temper, smashing cell phones and lobbing insults at colleagues. He once called studio executive Jeffrey Katzenberg "the eighth dwarf: Greedy." Post-college, Daniel worked as runner for a big-time bookie. (When his father died, Daniel was in jail for driving a car with stolen tags.) Stephen has abused drugs.

5 Baldwin Babes. By reputation, Baldwins play the field, sleeping around Hollywood, then settling down with a beautiful woman. Before marrying Basinger, Alec was known as a playboy and heartbreaker. He is most famous for dumping Northern Exposure star Janine Turner weeks before their wedding. Billy married Chynna Phillips of the pop group Wilson Phillips, after flings with Madonna and Jennifer Grey. Daniel's second wife is his Homicide co-star Isabella Hofman. Stephen is married to a Brazilian artist named Kennya Deodato.

6 Baldwin Exhibitionism. Physical modesty is not a Baldwin trait. Alec and Kim Basinger actually did the deed in their sex scenes in The Getaway (1994)--unheard of in Hollywood. All but one of Billy's major movies include shots of his rear, and frontal nudity scenes from his movie Sliver were trimmed at the last minute. In Threesome (1994), Stephen participates in a ménage à trois. (A very Baldwin coincidence: Both Stephen's Threesome and Billy's Three of Hearts [1993] are about bisexual love triangles.)

7 Baldwin Birth Order. No profile makes the obvious application of Frank Sulloway's controversial birth-order theory. Sulloway contends that firstborn children are moralistic, eager to please their parents, and easily angered. (All of which apply to Alec.) Middle children are compromisers. (Billy is said to be the family peacemaker.) And later-born offspring are rebellious (the case with Stephen). In Sulloway's theory, as in life, Daniel is the category-defying, black sheep Baldwin.