Kate and Gerry McCann will mark the fourth anniversary of their daughter Madeleine's disappearance privately with family and friends.
The couple are keeping a low profile as Mrs McCann, 43, prepares to publish her account of how the little girl vanished on a family holiday to Portugal in 2007.
Proceeds from the book - which is simply entitled Madeleine and goes on sale on May 12 - will boost their dwindling fund to search for their daughter. They also hope that the publication of the work will prompt people holding vital information about what happened to the child to come forward at last.
The McCanns, from Rothley, Leicestershire, are not giving any interviews to mark the anniversary of Madeleine's disappearance this year, although they will do some to promote their book.
Family spokesman Clarence Mitchell said: "It will be a private day marked with family and friends. The anniversary is normally a very low-key occasion at home for them." He added that there are no plans for them to return to Portugal for the sad four-year landmark.
The 384-page book, which Mrs McCann has written herself without the aid of a ghost writer, has a recommended retail price of £20 and is expected to become a best-seller.
It was originally due to be published last week but publishers Transworld postponed the release date by a fortnight to avoid clashing with the royal wedding.
Extracts from the book will be serialised by newspapers from this weekend before the book is published on Madeleine's eighth birthday.
Madeleine was nearly four when she vanished from her family's holiday apartment in Praia da Luz in the Algarve on May 3 2007 as her parents dined with friends nearby.
Despite a massive police investigation and huge publicity worldwide, she has not been found. The official Portuguese inquiry into Madeleine's disappearance was formally shelved in July 2008, although private detectives employed by the McCanns have continued the search.