In a corner of one of the first-floor rooms, a pianist tinkled "mostly cocktail music." He might have been another art object, but his hands were moving. On a sofa near the main door, three brown and tan pillows pushed together spelled out a simple message: "BE IT EVER SO HUMBLE, THERE'S NO PLACE LIKE THE VICE PRESIDENT'S HOUSE."

That's the way they felt at the National Commission on the international Year of the Child, so yesterday Joan Mondale hosted IYC state cooridinators from across the country, who had spent Thuesday and Wednesday in Washington at a White House briefing on IYC's progress.

Mixing with them were several governors' wives, who are honorary chairmen of IYC efforts in their states.

Jane Freeman, one of the 24 commisioners and the wife of Orville Freeman, former governor of Minnesota, said it was the commission's idea to invite governors' wives to play a special role in IYC affairs.

"If nothing else," confirmed Barbara Pomeroy, executive director of the commission, "a governor's wife gets publicity. The governor's wife is important and it is important in drawing attention to the needs of children."

Freeman praised the active role many of the wives are taking. Nowadays, she said, governors' wives act as lobbyists for special causes, but she remembers how things used to be.

"Anything you did," she said, "you did extremely gently."

Mondale gathered the group to make some brief remarks and introduce Jean Young, chairman of the commission, who had to leave immediately for the A.M.F. Youth "games in Richmond.

"This is a field that my husband worked very hard in when he was in the Senate," Mondale said.

As the guests returned to mingling, Ramona Carlin, first lady of Kansas, talked about how her efforts would be focused on the problem of adolescent pregnancy. She's also planning a children's art festival on the capitol grounds in Topeka with state coordinator Nancy Hodges.

"We're going to call it 'Oz II.' We're hoping to change the capitol into the Emerald City."

In another room, Honey Alexander, wife of Gov. Lamar Alexander of Tennessee, chatted about her long-time interest in the commission's work.

"In the campaign last year," she recalled, "I spent a lot of time researching children's issues." She and the IYC people back home have not decided, however, which children's issues will get special priority in Tennessee.

Beside her on a couch slept 2-monthold William Houston Alexander, her fourth Child.

"As you can see," she remarked, "I'm committed to children." CAPTION: Picture, Joan Mondale and Jean Young greet IYC commissioners, by John McDonnell -- The Washington Post