Margit Wennmachers, co-founder of Outcast Communications — a mid-size agency that handles high profile clients including Facebook and Yahoo — is leaving the agency to join venture capital firm Andreessen Horowitz as a partner.

Reports Kara Swisher of AllThingsD, “The move will make her one of a handful of women at high-profile venture outfits.” Outcast co-founder Caryn Marooney will now run the agency, which was acquired by holding company Next Fifteen Communications in 2005.

UPDATE: PRNewser just spoke with Marooney, who said, “We are always looking for great smart people at every level, but we’re not looking to replace or add a partner at this time.” She also sees opportunity in the move. “Being close to the venture community is something we’ve always done. As long as we can provide the best service for [companies] it can definitely be a fun win win situation,” she said.

The agency continues to see growth, recently picking up work with online music portal Vevo. Facebook director of communications Brandee Barker is also very happy with the agency’s work. “Facebook loves Outcast,” she said this past November.

Andreessen Horowitz is an Outcast Communications client.