For the first time, the Duke and Duchess of Cambridge have publicly appeared with all three of their children. The family of five made a joint appearance at the christening of Prince Louis, Prince William and Kate Middleton's third and youngest child together. This also marks Louis' first public appearance since his birth on April 23, when he left the hospital with his parents.William and Kate were seen entering the Chapel Royal in St. James' Palace in London alongside Louis and his older siblings, Prince George and Princess Charlotte. Kate wore a white Alexander McQueen dress and a white hat designed by Jane Taylor. Prince Harry and Meghan, Duchess of Sussex, (wearing an olive Ralph Lauren dress) walked in immediately behind them. The Archbishop of Canterbury, Justin Welby, was set to perform Louis' christening at the Chapel Royal. After the christening, the family is slated to travel to Clarence House, the official residence of Prince Charles, for portraits by photographer Matt Holyoak. Guests will also have a private tea reception, hosted by William and Kate, where they will be served a tier from their wedding cake. The christening itself is a small affair, with only family and close friends attending. Joining the Duke and Duchess of Cambridge are Harry and Meghan; Prince Charles and Camilla Parker Bowles, Duchess of Cornwall; Carole Middleton and Michael Middleton; Pippa Middleton and James Matthews; and James Middleton. Louis' godparents and their spouses are also in attendance. Queen Elizabeth and Prince Philip are not on the guest list, though, reportedly because of the queen's busy schedule, and Philip's retirement from royal duties.