His mother is German and his father is Italian, and their backgrounds had a major influence on his upbringing. His father produces comic books and comic arts . His mother was a legal secretary (before she began managing Leo's affairs.) They might be best described as liberal, pot-smoking hippies: "Whatever I did would be something they'd already done. I mean, my dad would welcome it if I got a nose ring."  "We're not the hippie family who only eats organic and the children meditate and go to a school of the arts. But we're not apple-pie and Republican, either."

Leo was educated at the Center for Enriched Studies and John Marshall High School, both in LA. He often cheated in school (especially in math), and seemed more interested in entertaining his classmates than in doing his homework. "School, I never truly got the knack of. I could never focus on things I didn't want to learn. I used to do break-dancing skits with my friend at lunchtime."

But his troubles concentrating in school didn't stifle his acting dreams. Leo's acting debut was on the television show Romper Room, at age five. Booted from the set because of his uncontrollable behavior, it would be eleven years until he would land a big-screen role. At age ten, on the way home from a casting call where he had just been rejected, he cried to his father, "Dad, I really want to become an actor, but if this is what it's all about I don't want to do it." Leo recalls his father put his arm around him and said, "Someday, Leonardo, it will happen for you. Remember these words. Just relax."

When searching for an agent Leo was further discouraged by the commercialism of the industry, exemplified by an attempt from one agent to alter his "wrong" haircut and change his ethnic-sounding name to Lenny Williams. He was finally signed at the age of fourteen, and struggled to break into the movie industry through obscure commercials and educational films such as "How to Deal With a Parent Who Takes Drugs" and "Mickey's Safety Club." He took part in over thirty commercials in all, and eventually procured guest appearances on such television shows as Lassie, The Outsiders, Roseanne, and Parenthood. Though he was cast in his first movie in 1991, Leo would rather forget his minor and embarassing contribution to Critters III altogether. At sixteen, he finally landed a successful, regular role as a homeless boy in the teen sitcom Growing Pains that lasted for a year. Though only a small part, Leo's performance proved he had great potential; he easily outshined the rest of the cast.

His big break was undoubtedly his leading role as Tobias Wolff in This Boy's Life. Though Leo's natural, brilliant performance in this "coming of age" movie didn't hit home at the box office, he gained instant recognition as a talented rising actor. Leo received a few prestigious awards for his performance (see below) and herein began his rise to fame.

Now given the opportunity to be picky about his roles, Leo chooses them carefully. He welcomes help from his father in sifting through the facile, mainstream roles most actors gleefully accept. Leo has turned down such commercially popular roles as Robin in Batman Forever, and continues to look for the more challenging "dark roles." "I want to take my time with each role and that's how you plan a long career rather than doing it all at once in a big explosion. I turned down a lot of movies about death and a few cheesy little comedies as well."

Leo is a favorite of many professional and amateur critics because of his unique ability to play the "boy/man" border with such ease and natural spontaneity. Though 25, Leo's boyish looks allow him to apply his learned experience and charm to younger roles that many of his immature competitors cannot handle. "The best thing about acting is that I get to lose myself in another character and actually get paid for it. It's a great outlet. As for myself, I'm not sure who I am. It seems that I change every day."