Def Jam co-founder, music mogul and social activist Russell Simmons, alongside film director/producer Brian Robbins (founder and president of Varsity Pictures, director of "Hardball," "Varsity Blues") and well-known music executive Steve Rifkind have partnered with Universal Music Group to launch All Def Music, a new "record" label whose sole focus is the promotion and development of artists via the medium of YouTube. Under the ADM umbrella, the partnership will also launch ADD Management. Rifkind has been named CEO of ADM and ADD Management. The launch was announced today in a statement from UMG.

The official launch of All Def Music is a concerted push behind the YouTube network (and underlying model of) All Def Digital that Simmons launched last year through his company Rush Digital Media. As well, a partnership between Simmons and Robbins on the venture, via Rush and Robbins' AwesomenessTV startup, was announced earlier this year. The pair had also collaborated on hip-hop documentary "The Show" in the mid-'90s.

Rifkind, who founded Loud Records in 1992 (home of the Wu-Tang Clan, Xzibit, Three 6 Mafia among others), had most recently signed a three-year deal with Universal in early 2011 to continue on as president of SRC, the hip-hop label he founded in 2002, before exiting in September of 2012, reportedly going on to help promote a new basketball league, though details on the fate of the league remain scarce.

“The exponential growth of Internet-based video has created a powerful new outlet for music and music-based content, and the launch of All Def Music is a part of our broader strategy to partner with some of the most experienced entrepreneurs in media and technology to identify future stars and develop powerful content on the world’s fastest growing media platform,” wrote UMG chairman Lucian Grainge about the new business and its attendant model.

Simmons echoed sentiments expressed in the initial launch of the ADD YouTube network, saying in a statement that "this is the most exciting new terrain for me, to move talent across all media platforms and I couldn’t have better partners in Brian and Steve, and the most innovative of music executives, Lucian Grainge.”

ADD Management's first announced signings are Spoken Reasons (born John A. Baker, Jr.), whose YouTube channel boasts 1.37 million subscribers,  and "suburban rapper" Asher Roth, who will be featured in an "unscripted music-themed show" titled "Lemonade."

This is a developing story – Billboard will update our coverage as soon more information is available.