Oct. 4, 2001 -- Rob Lowe was once the crown prince of the bad boys and a legendary party animal — until an infamous sex tape brought the bash to a halt.

"I loved fun. I spent my whole life in search of fun," he says. "I have not given up that part of myself."

But the 37-year-old actor has been tamed: On screen, he is the true believer and suffering heart, and off screen he has been sober for 11 years, still with Sheryl Berkoff, the woman he married 10 years ago. The couple have two boys.

Sowing His Oats

Settling down, Lowe tells Diane Sawyer, did not come easily. "I really felt like I had to jump on it while the getting was good," says Lowe. "For guys, I don't think you're ever ready … I don't think you wake up and go, 'You know, today's the day I'm going to get married. By God, I'm ready. My house is in order and it is time.'"

But, says Lowe, "I sowed my wild oats and I'm really O.K. with the fact that I'm never going to be with another woman again. That sits well with me."

The Brat Pack Days

In the 1980s, Lowe was part of the celebrity phenomenon known as "The Brat Pack," along with Demi Moore, Emilio Estevez, Judd Nelson and Ally Sheedy. In retrospect, the group looks like a survival experiment in drugs, drinking, and taking the dare.

"We were kids," Lowe recalls. "And we weren't built for speed."

Asked whether he was happy when he became famous, he says, "You know, the best way I can put it to you is that you think that when you make it, that when you have success … that's it's going to fill you up. And then it happens, if you're lucky, and you're still the same person."

In Lowe's case, that person was a good kid from a Methodist family who grew up in Ohio. He wanted to be a marine biologist until he saw a production of "Oliver Twist." Realizing acting was his dream, he started in community theater.

Commercials led to a TV role, and then in 1985, when he was 21, St. Elmo's Fire made him a million-dollar-per-movie heartthrob.

He was 24 when he attended the Democratic convention in Atlanta as a campaigner for presidential candidate Michael Dukakis. He was out one night at a club when he met two young women who agreed to be videotaped in his hotel room.

By morning the girls and the videotape were gone. The tape later became public, and it turned out that one of the girls was a minor. The girl's mother sued Lowe, who settled the case out of court. As part of the settlement, Lowe did community service. But the fawning and positive attention disappeared.

"I think part of it is that when you're young and when you're experimenting, whether it's with drugs, alcohol, driving too fast, sex, dropping out of school — whatever it is that you do to rebel … maybe somebody won't be looking and nobody will be the wiser," he says. "But maybe not. And you just have to know that."

Lowe says he felt alone, except for his family. "I'll never forget one of those things that my father said to me," he says. "My father said: 'You know what? We have had so many amazingly positive experiences that we would have never had, because you're famous. We can stand to have a couple negatives one too.'"

The scandal was "a bit of a test," Lowe says. "I really wanted to do the right thing by how I lived my life after that mistake."

A Career Comeback

Lowe's career sputtered until his friend Lorne Michaels asked him to open the season in 1990 on "Saturday Night Live." Ever since, he's been winning laughs from a new generation, starting with his role in Austin Powers: The Spy Who Shagged Me.

And now, as Sam Seaborn, his character on The West Wing, might say: Lowe knows that wisdom the first time around is luck; the second time it's character.

"I'm perfectly flawed … I've got tons of flaws," he says, citing his selfishness and self-absorption. "They're all actor flaws."

The best things about him? "I'm nice," he says. "I'm funny. And when I love, I love really deeply."