The couple announced Prince Harry will be his brother's best man, and Kate Middleton's younger sister Pippa will be maid of honor.
Among the bridesmaids and page boys are Camilla Parker Bowles' 3-year-old granddaughter and two of William's godchildren.
What they'll be wearing will be kept under wraps until the wedding day on April 29.
The announcements by St. James' Palace made it clear the April 29 wedding at Westminster Abbey will be a family affair that emphasizes the tight bonds between Britain's youthful princes and between Middleton and her younger sister.
Since Prince Harry loves to tease his older brother, his toast to the newlyweds is expected to be one of the highlights of the celebration. Will he poke fun at William's receding hairline? Will he mention other girls who once attracted William's eye? Stay tuned.
The Associated Press contributed to this story.