Joseph A. Kahl, a professor of sociology at Cornell from 1969 until his retirement in 1983, died Jan. 1 in Bethesda, Md., at age 86.

Kahl's influential 1957 textbook "The American Class Structure" defined the emerging field of social stratification. Kahl wrote the book in Mexico, where an unemployed Harvard Ph.D. could live cheaply. He fell in love with Latin America, according to his former student and co-author Dennis Gilbert, Ph.D. '77, a professor of sociology at Hamilton College.

"Joe had enormous enthusiasm for Latin America. He was fascinated by the region's struggle for social change and social justice," said Gilbert, who noted that Kahl and two other Cornell professors annually taught a popular graduate seminar on Latin America, which blossomed as a field of study after the 1959 Cuban revolution.

Born in Chicago in 1923, Kahl attended the University of Chicago (his studies were interrupted by World War II service in the South Pacific) and received a Ph.D. from Harvard University, where he also taught. He was "brought in as a star" to Cornell from Washington University in St. Louis, said Gilbert. "I came to Cornell -- as did a lot of other people -- because of him. For anybody in the social sciences interested in Latin American, he was the guy you wanted to have on your committee."

At Cornell Kahl served as chair of sociology and director of the graduate field. His other books include "The Deadeyes: The Story of the 96th Infantry Division," a semi-official account of his unit in the war; "The Measurement of Modernism," about changing values in Mexico and Brazil; and "Modernization, Exploitation, and Dependency: Germani, Gonzalez Casanova, Cardoso" about the seminal work of three Latin American sociologists.

Kahl retired to Chapel Hill, N.C., where he listened to opera and kept up his interest in Mexico and Latin America. The first edition of "The American Class Structure" paid for his house in Mexico. The eighth edition will be published this year with Gilbert as the sole author (he co-authored several editions with Kahl and then eventually took over the authorship after Kahl retired); Gilbert dedicates the book "to Joe Kahl, a fine teacher, a supportive colleague, and good friend."

In his letter resigning from the faculty at the age of 60, Kahl remarked: "As an opera lover, I had watched several great singers stay on too long, leaving memories of voices that had begun to fade, not voices in full bloom. I decided long ago to stop teaching before my voice gave out, and I am satisfied with my timing."