A book about a teenage boy coming to terms with his mother's cancer has become the first to triumph in twin awards for children's literature.
A Monster Calls by Patrick Ness has collected both the CILIP Carnegie and Kate Greenaway medals, for writing and illustration respectively.
Judges called the book "one of the defining books of its generation".
For Ness, it is a further triumph as he won the Carnegie last year and has become only the second writer to take the prize in successive years since it was launched in 1937.
The esteemed award has been collected by authors such as Philip Pullman, Terry Pratchett and Neil Gaiman in recent years. It was first won by Arthur Ransome for Pigeon Post, one of the books in the Swallows And Amazons series.
Jim Kay collected the Greenaway prize - founded in 1956 - for his artwork in Ness's book.
Rachel Levy, the chair of the judging panel, said: "A Monster Calls is outstanding in every way - Patrick Ness's story is exquisitely told with not a word out of place.
"Jim Kay's bold, haunting illustrations beautifully complement, and even expand the text.
"This is a book readers will remember and return to over and over again.
"It is, quite simply, one of the defining books of its generation."
Ness was inspired to write the book from a final idea of late writer Siobhan Dowd, who was awarded the Carnegie in 2009 - two years after her death.
The book tells the story of 13-year-old Conor who is trying to escape the spectre of his mother's illness.
Nominees for the respected awards - handed over at the Barbican in London - are compiled by library professionals.