As Middleton made her way down the aisle, Prince William faced forward toward the altar but his younger brother, Prince Harry, could not resist. Cameras captured him looking back and then appearing to whisper to his brother: "She is here now."
Michael Middleton, the bride's father, smiled as he accompanied his daughter out of the car. After they entered the Abbey, he turned to Catherine and asked: "Are you ready? You look great."
When Middleton joined William at the altar for the ceremony, he told her: "You look beautiful." And after the wedding, as the two got into the carriage as man and wife, it was reported that he said to her: "I am so happy."
It was the kiss seen around the world ... twice. The two stepped out onto the balcony of Buckingham Palace and waved at the crowds below. With the bridal party, the royal family and the bride's family behind and alongside them, Middleton and William kissed quickly.
The crowd cheered and started chanting "Kiss her again" and William obliged, planting a much longer smooch on his new wife, the duchess of Cambridge.
The couple left Buckingham Palace and headed to Clarence House in a vintage open-top Aston Martin -- with Prince William at the wheel.
ABC News staff contributed to this story.
Watch a special 2-hour edition of "20/20" at 9 p.m. ET tonight to look at the big day, the night-time celebrations, and what's next for the happy couple, with Barbara Walters.