Adolfo Suárez González, the conservative politician who helped steer Spain from dictatorship to democracy in the late 1970s, has died in a Madrid hospital following a lengthy neurodegenerative illness.

Adolfo Suárez González, the conservative politician who helped steer Spain from dictatorship to democracy in the late 1970s, has died in a Madrid hospital following a lengthy neurodegenerative illness.

By Ilan Brat, Christopher Bjork

MADRID—Adolfo Suárez González, the conservative politician who helped steer Spain from dictatorship to democracy in the late 1970s, died Sunday, aged 81, in a Madrid hospital following a lengthy neurodegenerative illness.

In 1977, Mr. Suárez became Spain’s first freely-elected prime minister after almost four decades of rule by General Francisco Franco, who died in 1975. A political insider, he gently broke with Franco’s party and worked with King Juan Carlos, who had succeeded the general as head of state, to guide the country through a period of economic and social upheaval and set the foundation for a peaceful transition to democratic rule.

He smiled readily and was easygoing, but willing to take risks. After the king handpicked him in 1976 to lead a provisional government, Mr. Suárez helped legalize the Communist Party, an enemy of the Franco regime. The move angered the military hierarchy, prompting fears of a coup, but it was part and parcel of Mr. Suárez’s governing strategy. A lawyer by training, Mr. Suárez saw the legalization of the Communists as a step toward a new constitution with ample public support.

“Thanks to the king, he was able to do what he most wanted,” said Adolfo Suárez Illana, his oldest son. “These two men changed the course of history.”

The photogenic Mr. Suárez, then 43 years old, won the 1977 elections by forming a political party, the Union of the Democratic Center, that united conservative and progressive political factions. His government spearheaded a group of political accords between leftist and conservative parties that facilitated freedom of speech and association, liberalized parts of the economy and worked to tame soaring inflation.

Guided by Mr. Suárez and others, a group of seven “wise men” representing a cross-section of the country’s political parties drafted the current constitution. Nearly 90% of Spain’s voters approved it in a referendum in 1978.

Mr. Suárez was born in Cebreros, a small town in central Spain, to a family of limited means. After he finished law school, Mr. Suárez joined Franco’s political party and climbed the ranks to become its secretary-general.

General Franco’s death left him in political limbo until the king, knowing his democratic intentions, picked Mr. Suárez over two older Franco loyalists.

Mr. Suárez won a second election as prime minister in 1979 but his political coalition soon began to disintegrate amid economic and social tumult. His resignation in early 1981 came weeks before some members of the military staged a failed attempt to take control of the government. He faded from the political spotlight after a new party he started won only a few seats in parliament.

The former prime minister valued simplicity, said José Luis Leal, who was finance minister under Mr. Suárez. In a country where lunch is the major meal of the day, Mr. Suárez ate little at midday, often only an omelet and a glass of orange juice. He also forwent hiring a chef of haute cuisine when he occupied the Moncloa Palace, Spain’s equivalent of the White House, according to Mr. Leal. “He didn’t care about any of that,” said Mr. Leal.

Until he became incapacitated by a degenerative neurological disease 11 years ago, Mr. Suárez maintained frequent contact with an array of the country’s political leaders, offering counsel from behind the scenes.

“He was a sort of go-between in difficult political circumstances,” said Ernesto Ekaizer, a journalist with Spain’s El País newspaper who has written several books on Spanish politics.