In 2001 Large Pro produced “You’re da Man” and “Rewind” for Nas’s Stillmatic album. He first played Nas the beat for “You’re da Man” while Nas was working on Nastradamus a few years prior. Nas chose the beat but decided to save it for a later project. Large Professor also used the same vocal sample from the chorus on the song “The Man” for his 1st Class album.

In 1996 Large Professor completed his debut solo album The LP for Geffen Records. It was promoted by the singles “The Mad Scientist” and “I Juswannachill”. After several delays, the album was shelved and later released as a bootleg version in 2002. An official release of the album finally came out in 2009, thirteen years after its original intended release date.

In 1994 Large Professor produced three of the ten songs on Nas’s Illmatic (“Halftime”, “One Time 4 Your Mind”, and “It Ain’t Hard To Tell”), the most of any producer involved with the album. According to an interview with Busta Rhymes, the “Halftime” beat was originally intended for him. Thought he liked the beat, he didn’t end up using it and later regretted it after hearing “Halftime”. While describing the making of the song in an interview Large Pro said, “I mean, we just wanted to put something gritty out there to the world, and those drums—that’s what it was at that time. It was that gritty, muffled out, because the Hip Hop that we grew up with… We grew up with park jam tapes and things like the fidelity of these tapes.” He was so instrumental in the making of Illmatic that Nas wanted to give him an executive producer credit, but he refused.

In 1992, their success allowed them to record “Fakin’ the Funk”, a track on the White Men Can’t Jump motion-picture soundtrack. Because of business differences, Large and Main Source quietly parted ways and Large went on to sign with Geffen Records.

Main Source recorded one album with Large called Breaking Atoms, which was released in 1991. It included hits such as “Just Hangin’ Out”, “Looking at the Front Door”, and featured Nas’ first public appearance on a track called “Live at the Barbeque”, along with Akinyele and Joe Fatal. Large Professor now considers “Looking at the Front Door” one of the most emotional records of his career, later saying “That’s a deep record. At that time in life, I was eighteen years old. It was a kid with a pure heart, just writing, and putting his soul out there for the world.”

During and after his tenure with Main Source, he worked with Pete Rock & CL Smooth, and he produced a number of tracks for Nas, Busta Rhymes, Masta Ace, The X-Ecutioners, Tragedy Khadafi, Big Daddy Kane, Mobb Deep, A Tribe Called Quest, and others during the 1990s. During this time he handled a significant amount of production on several projects for other artists. In 1993 he produced Akinyele’s entire Vagina Diner album, which experienced some modest commercial success at the time of its release. Though the album did well at first, The Source later wrote an article criticizing the song “I Luh Huh”, in which Akinyele considers pushing his pregnant girlfriend down the stairs as a form of abortion. The ensuing backlash for the controversial lyrics hurt the album’s performance. Akinyele wrote a response in the next issue defending the song and pointing out that the violent ideas in the songs are just thoughts, and he ends the song by saying “Just cause I talk this shit don’t get me wrong, Yo, I still luh hur.”

Large Professor is the stage name of William Paul Mitchell (born March 21, 1972), an American rapper and record producer also known as Large Pro and Extra P. Based in New York City, he is known as a founding member of the underground hip hop group Main Source and as mentor and frequent collaborator of Nas. About.com ranked Large Professor #13 on its Top 25 Hip-Hop Producers list.