Jessica Biel Pictures in Valentino at 2011 Charity: Ball

Jessica Biel flashed a smile at last night's Charity: Ball in NYC. The star rubbed shoulders with fellow philanthropic celebs like Sophia Bush at the bash, which raised money for charity: water's efforts to bring clean, safe drinking water to those in need around the world. It was Jessica's latest act for the cause, after she helped coordinate a Live Earth run in 2009 and climbed Kilimanjaro in 2010 to bring attention to the global water crisis.

Jessica chose a sheer black dress for the occasion. It was designed by Valentino, the same fashion house who outfitted her for the NYC premiere of New Year's Eve with Sarah Jessica Parker and Zac Efron last week. Jessica handled press rounds in the Big Apple and the UK for the ensemble film, but Zac picked up promotional duties today by heading to Japan for more events.