The ceremonies to honor Queen Elizabeth II, from the memorial service to lying in state, follow strict rules of protocol. Her funeral service will be no exception -- down to the royal dress code.
Members of the royal family will all be in attendance, including the queen's four children, her eight grandchildren and their spouses, along with several U.K. prime ministers including the current and past ones. It is unclear if the queen's great-grandchildren will attend.
What the royal family wears to the funeral will be dictated largely by tradition.
Military uniform: As working members of the royal family, three of the queen's children -- King Charles, Princess Anne and Prince Edward -- and her grandson Prince William will be dressed in military uniform at the queen's funeral, according to Buckingham Palace.
Prince Andrew and Prince Harry, the queen's son and grandson, respectively, are the only living members of the queen's immediate family to have served in the military in wartime. Though they both will not be in uniform at the funeral as they are no longer working royals.
With rare exceptions, both have not worn their uniforms at the main ceremonial events during the mourning period for the queen. Prince Andrew was dressed in uniform when he and his siblings held vigil at the queen's coffin, and Prince Harry will be allowed to do the same on Saturday when the queen's grandchildren hold vigil at her coffin.
All-black: An all-black formal dress code is "always respected" by the royal family at state funerals, according to Debrett's, the self-proclaimed "record-keeper and chronicler of British society" and royal authority. For women, that means black knee-length dresses or coats and black hats. For men not in military attire, that means black morning coats.
On Monday, members of the royal family, including Camilla, the Queen Consort; Kate, the Princess of Wales; Meghan, the Duchess of Sussex; and Sophie, the Countess of Sussex, will wear black, as they have since the queen's death was announced.
Veils: Long, black, face-covering veils are also a common sight at state funerals, a tradition that is believed to have started with Queen Victoria.
At King George VI’s funeral in 1952, the Queen Mother, Queen Elizabeth II and Princess Margaret all memorably wore waist-length black veils, which were a "somber reminder of the momentousness of the occasion," Debrett's said.
For Princess Grace of Monaco's funeral in 1982, Princess Diana wore a black straw hat with a black veil.
For the queen's funeral, the female members of the royal family are likely to follow tradition in wearing black veils -- known as mourning veils -- that fully or partially cover their face.
ABC News' Katie Kindelan contributed to this report.