Tuesday, January 28, 2014 at 9:25 PM 
The First Lady is attending President Obama's State of the Union address on Capitol Hill in Washington, D.C. this evening. For the occasion, Mrs. O is wearing an emerald green dress with stripe detailing and a cropped jacket. A black belt at the waist accessorizes the look.
Update: Per the Huffington Post, Mrs. O wears Alaia.
Alaia Monday, October 28, 2013 at 11:19 AM 
The First Family attended Sunday church services at Saint John's Church in Washington, D.C. this weekend. For the outing, Mrs. O wore a deep plum Alaia dress and jacket, paired with tall black boots. The dress was first seen during an Oprah special in 2009, here.
Alaia Friday, November 9, 2012 at 10:36 PM 
The Obamas traveled back to the White House on Wednesday just hours following the election. Boarding Air Force One at Chicago O'Hare International Airport, Mrs. O revisited two style favorites: her famed Alaia belt and a wool and silk boucle coat from Duro Olowu.
Alaia, Duro Olowu Wednesday, September 26, 2012 at 10:39 PM 
Official White House Photo by Sonya N. Hebert
The Obamas attended a United Nations General Assembly reception at the Waldorf Astoria on Monday evening. For the event, Mrs. O rewore an Alaia frock, previously seen here and here, paired with a low heel for the occasion. Pictured above, the president and first lady pose with UK Foreign Secretary William Hague.
Something to ponder: I've noticed that the first lady is rewearing key pieces from her closet quite a bit lately, perhaps more than usual. Is it a style savvy approach to minimize media focus with the election upcoming? Or an effort to get mileage out of investment pieces? Maybe a little of both?
Alaia Tuesday, May 15, 2012 at 10:08 PM 
It's been a sport-centric week for the First Lady thus far. Yesterday, Mrs. O addressed athletes from Team USA at a press conference held in Dallas, Texas. Today, she was back to the White House to host a Let's Move event honoring the LA Galaxy.
On the style front, black and white appears to be the palette du jour. Mrs. O paired an oversized flower pin with a striped top, blazer and white trousers (not shown) in Dallas. For today's White House event, Mrs. O wore her signature Alaia belt in white with a Moschino bow blouse and black trousers.
Update: Reader Elizabeth identifies Mrs. O's blazer as Moschino, available here.