Bhumibol Adulyadej, rules Thailand (Siam) as King Rama IX. Born 5 December 1927 in Cambridge, Massachusetts, Bhumibol was the son of Prince Mahidol of Songkhla and the grandson of King Chulalongkorn. Prince Mahidol, who died when Bhumibol was only a year old, was studying public health and medicine at Harvard University when his son was born. Five years after Mahidol's death, Bhumibol, his sister, and his brother Ananda (later Rama VIII) left Thailand to study in Switzerland.

Throughout World War II, the family continued to live in Switzerland, returning briefly to Thailand in early December 1945. Tragically, four days before he was to leave for Switzerland to complete his studies, the young Ananda died in his chambers of a mysterious gunshot wound. Bhumibol became king but did not remain in Thailand to witness the ensuing political turmoil; he and the rest of the family returned to Switzerland. To prepare for his future responsibilities, Bhumibol switched from scientific studies to law and political science at the University of Lausanne. As monarch, Bhumibol is still keen on agricultural research (the palace operates an experimental farm in Bangkok), hydraulic engineering, the practical application of artificial rain, and the manufacture of synthetic fuels.

In 1950, Bhumibol interrupted his studies and returned to Thailand to marry M.R.W. Sirikit Kitiyakorn. On 5 May of that year he was crowned Rama IX. The king has a son and three daughters, two of whom, Crown Prince Vajiralongkorn and Crown Princess Maha Chakri Sirindhorn, have been designated heirs apparent to the throne.

As a constitutional monarch, Bhumibol symbolizes the unity of the Thai nation. His long reign has allowed him to develop an important role for the monarchy. His status and prestige were greatly enhanced during the regime of Prime Minister Sarit Thanarat (1958-1963), during which a symbiotic relationship between king and the military regime was institutionalized. Since that time, the throne has exercised direct and indirect legitimizing prerogatives during times of political crisis and instability. Members of the royal family are active in charitable organizations and cultural groups. They have become active patrons of the conservative and nationalistic village scout movement, which played pivotal roles in political events of the late 1970s.

Following the ouster of the government of Thanom Kittikachorn in October 1973 and the ensuing political polarization, the royal family became more involved in the machinations of faction politics in Thailand. In fact, the conservative Thanin Kraiwichien government, formed after the army coup of 6 October 1976, has the tacit support of the throne. The most recent coup, the Young Turks' coup of 1 April 1981, illustrated the importance of monarchical support: the young army officers game up their attempt to overthrow the government by force when the queen made public her support of the incumbent Prem government. Although Bhumibol himself is still respected and revered by his subjects, open criticism and ridicule have been leveled at some members of the royal family.