Mark White, who as governor of Texas from 1983 to 1987 championed public education laws that limited class sizes, increased teachers’ pay and introduced basic skills tests for high school students, died on Saturday in Houston. He was 77.

Mark Miller, a longtime friend and political consultant to Mr. White, said the cause was a heart attack.

Mr. White, a Democrat, was the attorney general of Texas from 1979 to January 1983, when he became governor after defeating William P. Clements, the Republican incumbent. (Mr. Clements returned to defeat him in 1986.)

In his four years in office, Mr. White won legislation requiring high school students to pass basic skills tests to graduate; establishing competency tests for public-school teachers and raising their salaries; capping class sizes in elementary schools; and increasing taxes by $4 billion to finance it all. Facing an economic downturn caused by plummeting oil prices, he also tried to wean the state off its dependence on oil and lure other industries to Texas.