The royal couple made a sentimental visit to the college town where they met a few years back, telling the crowd of about 3,000 that Saint Andrews was "the best university in the world."
"This is a very special moment for Catherine and me," William said. "It feels like coming home."
The Daily Telegraph said Saturday that the trip was the first to Saint Andrews for the couple since their graduation in 2005. The occasion was marked by the establishment of a scholarship fund in their name.
The newspaper said William and Kate, who was dressed in red, worked the crowd for more than a half an hour.