The First Lady joined Secretary of State John Kerry to honor recipients of the International Women of Courage awards on Friday. This year's recipients include (from left to right in the front row): Afghan National Interdiction Unit, First Sgt. Malalai Bahaduri; Campaign for Democracy President Josephine Obiajulu Odumakin of Nigeria; Russian human rights activist, journalist Elena Milashina; Elman Peace and Human Rights Centre Executive Director Fartuun Adan of Somalia and National Autonomous University of Honduras Rector Julieta Castellanos.
For the occasion the First Lady wore a printed wrap dress that she has worn at least twice before, seen here and here last year. In the past commenters have suggested that the dress is Etro, which seems about right, but I've not been able to confirm. A gold star awaits anyone who can!
"Remarks by the First Lady at the International Women of Courage Awards" [White House]
Update: Hooray for reader Pam, who has unearthed a bit of digital evidence here. It appears the dress is indeed Etro.