The first lady had participated in the National Zoo's announcement earlier this year that pandas would be returning to Washington. They arrived in the nation's capital in mid-October and Jill Biden donned the panda suit Wednesday as a "welcoming gesture," the White House said.
Jill Biden added an educational theme to the event and named it "Hallo-Read" to help encourage reading. She has been a teacher for 40 years. Earlier Wednesday, she read a short story about spooky pumpkins to a group of costumed children gathered on the lawn.
She and the president later ventured outside at sunset and spent about an hour handing out treats. Biden, in a suit and tie, dropped boxes of White House Hershey's Kisses chocolates in the kids' tote bags while the first lady handed out copies of "10 Spooky Pumpkins."
Up to 8,000 people, including students and children tied to the military, were expected to pass through the White House gates during the day.
A large orange moon and a sign that said "Hallow-Read at the White House" decorated the south face of the executive mansion. The decorations also included cardboard representations of Willow, the family cat who is rarely seen in public, and stacks of books. Giant pumpkin decorations flanked the door.
Biden dropped his bid for reelection in July. He leaves office in January.