The Pope, who is recovering from a throat operation, did not speak as he blessed the faithful several times. Springlike weather allowed him to open wide his window just before midday today.
This was the Holy Father's first public appearance since his return to the Vatican on Sunday, more than two weeks after his Feb. 24 tracheotomy.
The Pope, seated in an armchair, had a calm expression, confirming Vatican spokesman Joaquín Navarro Valls' report about his health and positive convalescence.
When the Holy Father appeared, he was greeted with applause by those present, mostly Poles and Americans. Earlier, Polish children had intoned songs in his native language.
Some 1,000 pilgrims had gathered in the square, even though the general audience had been canceled a day earlier. The Pope did not disappoint their hopes of catching a glimpse of him.
As Holy Week approaches, John Paul II's next scheduled appearance is to impart his tradition blessing to the world on Easter Sunday.