King Bhumibol Adulyadej acceded to the throne on 9 June 1946 after his brother, King Ananda Mahidol, died in a still unexplained shooting accident at the Royal Palace in Bangkok.
He was born in Cambridge, Massachusetts, where his father was studying, and he was later educated in Switzerland. He returned there to finish his studies before returning to Thailand where he was crowned in May 1950.
The status of the monarchy had been in decline since the abolition of absolute monarchy in 1932, and then the abdication of King Prajadhipok, King Bhumibol's uncle, in 1935.
In his early years King Bhumibol was overshadowed by a series of powerful military leaders. But with the support of other royal princes and sympathetic generals he rebuilt the monarchy's profile, making a series of tours to outlying provinces, and through numerous royal projects that established his lifelong concern with agricultural development.
In 2006, then UN Secretary General Kofi Annan presented him with the United Nations' first Human Development Lifetime Achievement Award.