Karl A. Menninger, 96, America's preeminent psychiatrist who played a major role in bringing the practice of psychiatry into the mainstream of modern medicine, died of cancer yesterday at Stormont-Vail Regional Medical Center in Topeka, Kan.

Menninger was one of psychiatry's most articulate and prolific champions and the author of 13 books and countless papers and articles on various aspects of mental illness and human behavior. It was only during Menninger's lifetime that treatment for mental disorders became widely available, and Menninger himself was a major influence in bringing that development about.

When he began his career, psychiatry was little known in this country and less understood, and many regarded it with profound suspicion. His work brought about profound changes in the way Americans viewed mental illness.

For 40 years, Menninger was the guiding genius of the Menninger Clinic in Topeka, one of the world's leading psychiatric research, teaching and treatment facilities, which he founded with his father.

His first book, "The Human Mind," was published in 1930, and it launched Menninger on a lecture and writing career that would last the better part of the next half century. He described the book simply as "the conception I have of the human personality." It included dozens of case studies from his own practice, examples from the lives of ordinary people in towns and cities across America. The book remained in print for decades, and it influenced the thinking of a generation of young psychiatrists.

Noted psychoanalyst Erik Erikson once said of it and Menninger's other writings that "Karl Menninger translates Freud into American literature." Others said Menninger was "more Freudian than Freud." The American Psychiatric Association called him "America's greatest living psychiatrist."

"People think I invented psychiatry and made millions," Menninger said in a 1977 interview with the Associated Press. "I didn't invent psychiatry, but yes, I made millions. But I don't have it." The money, he said, all went back into the foundation that operates the clinic.

It was Menninger's conviction that many of the same principles that governed the behavior of individuals also could be applied to the behavior of nations. He was convinced that psychiatry could not divorce itself from the problems of the world, and throughout his life he was active in a variety of social causes.

In his eighties and even into his nineties, he was outspoken on the dangers of a nuclear holocaust. In a 90th birthday interview with The Washington Post, he described fighting among nations as "the single greatest mental health problem in the world today."

Earlier, he had been passionate on the issue of prison reform. He addressed that subject in a lecture series and in one of his better known books, "The Crime of Punishment" (1968), in which he argued that "you don't rehabilitate a man by beating him." He was an early activist in such social causes as civil rights and conservation.

Karl Augustus Menninger was born July 22, 1893, in Topeka, the oldest of three sons of a physician in general practice. He attended Washburn College and graduated from the University of Wisconsin. He graduated from Harvard Medical School in 1917.

After an internship at Kansas City General Hospital in Missouri he returned to Massachusetts and taught at Harvard and Tufts medical schools, worked at the Boston Psychopathic Hospital and studied at Harvard under Ernest Southard, one of the eminent psychologists of that period.

After Southard died, Menninger returned to Topeka, where he practiced medicine with his father. The two Menningers believed in the advantages of a group medical practice where a variety of services would be available. As their practice began to focus increasingly on the mentally ill, the Menningers began to look around for a special setting in which to treat their patients. They persuaded a group of Topekans to form a corporation to finance the purchase of a farm just west of the city limits.

Their hospital and sanitarium there was chartered in 1925, the same year that the Menningers opened the Southard School for research and teaching in child psychology.

Over the years the Menninger facility developed a reputation for high-quality care and research, and Topeka became a national center of psychiatry. In 1941, the Menningers established the Menninger Foundation, a nonprofit organization for training, research and public education in psychology and psychiatry.

Menninger, meanwhile, had become an evangelist of psychiatry. "Once let thinking people realize what a better understanding of human nature can do in combating unemployment, religious fanaticism and mass hysteria, and there would be a demand for psychiatric services one hundred times greater than the present supply. Such an awakening is imminent," he said on the occasion of the founding of the Menninger Foundation. In the years since Menninger made that prediction, the number of psychiatrists practicing in the United States has grown from fewer than 4,000 to more than 30,000.

He followed up "The Human Mind" with two other popular books, "Man Against Himself" and "Love Against Hate," the former an examination of the self-destructive tendencies that are embedded deep within each human psyche, and the latter an exploration of those aspects of the human personality that can enable love to overcome hate and man's tendencies toward self-destruction. He also wrote frequently for such general circulation magazines as Ladies Home Journal, the New Republic and the Nation.

During World War II, the government asked Menninger for help in assessing the need for psychiatric care for servicemen. In 1945, he agreed to help establish the Winter Veterans Administration Hospital in Topeka as a psychiatric teaching center and a pilot hospital for the VA. He organized the psychiatric staff and later became senior consultant in psychiatry. The hospital became the VA's premier psychiatric facility.

Known as "Dr. Karl" to friends, colleagues and students, Menninger was a prodigious worker who was said to have been able to carry on a conversation, edit a paper and keep two secretaries busy dictating answers to correspondence, all at the same time. He could be cantankerous and given to temper tantrums, and he once kept a lecture audience waiting 30 minutes while he organized a search for someone who had usurped his parking space.

In 1965, he resigned as operating director of the Menninger Foundation, but he stayed on as chairman of the board. He continued to keep an ambitious writing and lecture schedule and to arrive at the office at 8:30 each morning until an operation for a brain tumor in 1976 and two subsequent mild strokes forced a reduction in his workload.

He received a Medal of Freedom, the nation's highest civilian award, from President Carter in 1981. With his father and his brother, he was represented in the Wilson Memorial Window of the Healing Arts, dedicated in 1979 at Washington Cathedral. Menninger and Albert Schweitzer were the only living subjects to have been represented in a window of the cathedral.

"Nothing of human concern is really outside of psychiatry," Menninger once said, explaining that he considered everything he did, even leisure activities, related to his work. "My favorite recreation is watching things grow on my tree farm, which I have tried to make into a bird refuge, because birds are as much a part of trees as leaves and blossoms and fruit."

In 1916, Menninger was married to Grace Gaines. That marriage ended in divorce.

Survivors include his wife of 49 years, Jeanetta Lyle Menninger of Topeka; three children of his first marriage, Robert G. Menninger, a Topeka psychiatrist, Julia Gottesman of Santa Monica, Calif., and Martha Nichols of Cheyenne, Wyo.; a daughter of his second marriage, Rosemary Menninger of Topeka; and nine grandchildren.