In recent years, Dr. Wright’s focus had shifted “to the democratization of the economy and to the ruling class,” said Mitchell Duneier, a former Madison colleague who is now chairman of Princeton’s sociology department.

Dr. Duneier, who interviewed Dr. Wright in December for a sociology textbook, quoted him as saying:

“If I were to write a 50-page text on how to think about class in the 21st century, I would begin by saying the problem of class is not the problem of the poor, the working class or the middle class. It’s the problem of the ruling class — of a capitalist class that’s so immensely wealthy that they are capable of destroying the world as a side effect of their private pursuit of gain.”

In addition to scholarship, Dr. Wright loved teaching, and his courses attracted many non-Marxists. When he accepted the university’s distinguished teaching award in 1998, he said his best ideas came from dialogue with students.

“Scholarship remains a passion,” he said, “but teaching is a joy.”

Erik Olin Wright was born on Feb. 9, 1947, in Berkeley, Calif. He grew up in Lawrence, Kan., where his father, M. Erik Wright, and his mother, Beatrice Ann (Posner) Wright, were professors of psychology at the University of Kansas, although his mother’s appointment was delayed several years because of an anti-nepotism policy.

Erik was planning to attend the University of Kansas and, because of his advanced studies, would have entered as a junior. But a family friend gave him an application to Harvard as a gift. He applied and was put on the wait list. In the meantime, he won first place in mathematics at the 1964 National Science Fair (now called the Intel International Science and Engineering Fair) with a project on Möbius strips.

He was accepted at Harvard, received his bachelor’s degree in social studies in 1968 and studied history for two years at Balliol College, Oxford. He met Marcia Kahn at Harvard; they married in 1971.

In addition to his wife, Dr. Wright is survived by two daughters, Jennifer Wright Decker and Rebecca Wright; a sister, Colleen Rand; a brother, Woodring Wright; and three grandchildren.