Dr. Ellis (he had a doctorate but not a medical degree) called his approach rational emotive behavior therapy, or R.E.B.T. Developed in the 1950’s, it challenged the deliberate, slow-moving methodology of Sigmund Freud, the prevailing psychotherapeutic treatment at the time.

Where the Freudians maintained that a painstaking exploration of childhood experience was critical to understanding neurosis and curing it, Dr. Ellis believed in short-term therapy that called on patients to focus on what was happening in their lives at the moment and to take immediate action to change their behavior. Neurosis, he said, was “just a high-class word for whining.”

“The trouble with most therapy is that it helps you feel better,” he told The New York Times in an interview in 2004. “But you don’t get better. You have to back it up with action, action, action.”

If his ideas broke with conventions, so did his manner of imparting them. Irreverent, charismatic, he was called the Lenny Bruce of psychotherapy. In popular Friday evening seminars that ran for decades, he counseled, prodded, provoked and entertained groups of 100 or more students, psychologists and others looking for answers, often lacing his comments with obscenities for effect.

His basic message was that all people are born with a talent “for crooked thinking” — distortions of perception that sabotage their innate desire for happiness. But he recognized that people also had the capacity to change themselves. The role of therapists, Dr. Ellis argued, is to intervene directly, using strategies and homework exercises to help patients first learn to accept themselves as they are (unconditional self-acceptance, he called it) and then to retrain themselves to avoid destructive emotions — to “establish new ways of being and behaving,” as he put it.

His methods, along with those of Dr. Aaron Beck, a psychiatrist who was working independently, provided the basis for what is known as cognitive behavior therapy. A form of talk therapy, it has been shown to be at least as effective as drugs for many people in treating anxiety, depression, obsessive-compulsive disorder and other conditions.

His admirers credited Dr. Ellis with adapting the “talking cure,” the dominant therapy in extended Freudian sessions, to a pragmatic, stop-your-complaining-and-get-on-with-you-life form of guidance later popularized by television personalities like Dr. Phil.