Photos: Michelle Obama goes formal

First Lady Michelle Obama wore a shimmering silver sheath by Zac Posen to the annual White House Correspondents Gala on April 25.

The first lady showed her toned arms and shoulders in a frothy white confection by Marchesa at the White House Correspondents Gala on May 3, 2014.

To welcome French President Francois Hollande for a state dinner on Feb. 11, 2014, Michelle Obama wore a custom gown by Carolina Herrera with a beaded top and “liberty blue” skirt.

For her husband’s second inauguration ball in 2013, Michelle Obama selected a red draped gown by Jason Wu.

At the Kennedy Center honors in 2012, Michelle Obama wore a high-waist gold lame gown by Michael Kors.   (Brendan Hoffman / Getty Images)

President Barack Obama arrives with First Lady Michelle Obama, clad in a mauve Halston slip dress, at the White House Correspondents’ Assn. annual dinner on April 30, 2011.   (Chris Kleponis / AFP/Getty Images)

An off-the-shoulder teal gown by Marchesa with a turquoise and silver necklace by Tom Binns was Michelle Obama’s choice when she and the president welcomed British Prime Minister David Cameron and his wife, Samantha, to a state dinner in 2012.   (Mark Wilson / Getty Images)

For a state dinner for South Korean First Lady Kim Yoon-ok and President Lee Myung-bak, Michelle Obama chose a gown by Korean American designer Doo-Ri Chung.   (Alex Wong / Getty Images)

President Barack Obama and First Lady Michelle Obama, wearing an ivory Naeem Khan gown, stand alongside German Chancellor Angela Merkel and her husband, Joachim Sauer, before a state dinner in 2011.   (Saul Loeb / AFP/Getty Images)

First Lady Michelle Obama wore a Naeem Khan multi-colored strapless print dress accessorized with gold earrings by Carla Amorim to the 2012 White House Correspondents’ Assn. Dinner in 2012.

Michelle Obama drew flak for wearing this scarlet Alexander McQueen gown -- because he was a European designer -- to a state dinner honoring Chinese President Hu Jintao in 2011.   (Saul Loeb / AFP/Getty Images)

The first lady wore a cheerful red jersey gown by Prabal Gurung to the White House Correspondents’ Dinner in 2010.

For a state dinner honoring Mexican President Felipe Calderon and his wife, Margarita Zavala, in 2010, Michelle Obama wore a shimmery blue belted town by Peter Soronen.

President Barack Obama and First Lady Michelle Obama wait to welcome India’s Prime Minister Manmohan Singh and his wife, Gursharan Kaur, to a state dinner in 2009. Michelle wore a handmade gold Naeem Khan gown with sterling silver applique.

Photographer Doug Mills of the New York Times stands next to First Lady Michelle Obama, who is wearing a hot pink sheath to the White House Correspondents’ dinner in 2009.

First Lady Michelle Obama wore a one-shoulder white gown by Jason Wu to the Midatlantic Regional Inaugural Ball in 2009.