For a century, management has evolved from an art to a science and back again. Along the way, the concepts have evolved, too, from assembly line to business process re-engineering. There's been horizontal organization, vertical organization, and even no organization. But the goal has been roughly the same: to balance people, profits, and technology for maximum productivity. And still, theories of how best to do that come and go. "The shelf time of each fad seems to be shorter and shorter," says Stuart Crainer, author of The Management Century and a dozen other management books.

The fleeting nature of such ideas begs the question: Is the trend of business trends coming to an end? That's doubtful. Management theories date to the 19th century, when the size and far-flung nature of the new railroad companies engendered the first professional managers, as well as the first management guru. The time and motion studies of Frederick Taylor, who advised companies such as Bethlehem Steel and DuPont, allowed industry to scientifically divide manufacturing processes into small, efficient units of work.

No utopia. Taylorism, as it's known today, was immensely successful and brought fame to both its founder and Henry Ford--whose Taylorist assembly line churned out Model T's at a remarkable and economical pace. Yet Taylorism had a downside: It essentially transformed workers from skilled craftsmen into factory cogs. "The unions raised holy hell about Taylorism," says Thomas McCraw, professor of business history at Harvard Business School. Ironically, Taylor himself was a utopian. "He thought the profitability brought about through his methods would eliminate class structure and struggle," adds McCraw.

Taylor's work did not address marketing. Neither did Ford, who offered his Model T in any color as long as it was black. After taking the helm at GM in 1923, Alfred Sloan proceeded to sell cars in various models and colors. Consumers loved them, allowing GM to beat Ford in the marketplace for decades. "For the first time it was putting the customer, rather than the production process, at the center of the equation," says Gary Hamel, a management guru and coauthor of Competing for the Future.

Sloan's bureaucratic method decentralized management, pushing the decision-making process downward and focusing it on products, not processes. The method gained wide adoption following World War I, when companies including Standard Oil and Sears, Roebuck were seeking a way to handle overcapacity.

The bureaucratic method provoked its own backlash. William Whyte's 1956 book The Organization Man and Sloan Wilson's 1955 novel The Man in the Gray Flannel Suit captured the discontents of the 1950s workplace, with its mind-numbing conformity and resulting suburban anomie.

The counterattack: A new approach with a human face was born. Often called the human-relations movement, it was spawned by legendary thinkers like Peter Drucker and Douglas McGregor. Work, according to McGregor's influential Theory Y, should be a source of satisfaction for employees motivated by meaningful objectives. Suddenly, personnel departments, which once only hired and fired, became human resources divisions responsible for nurturing workers and their careers.

Most workplaces today are a combination of Taylorism, Sloan's approach, and the more modern practices of Drucker and McGregor. But shorter-lived trends have left their mark. The 1980s spawned a deluge of business books and fads, partly a result of a growing management-consulting industry that sought fresh products to peddle. Some were a response to Japan and Europe, which were providing serious competition to U.S. companies.

In Search of Excellence, an influential 1982 book by two McKinsey consultants, described practices common to excellent companies. Other books, including The One Minute Manager, which directed managers to share feelings and dole out daily praise in one-minute increments, faded quickly. Many trends were merely old wine in new bottles, while others were imports from the East, which began taking market share from U.S. automakers in the 1980s.

B-school or bust. The early 1990s brought the re-engineering craze. It coincided with a recession and thus meant layoffs, or "rightsizing" as the consultants branded it, for many. Revenue for the consultants who touted re-engineering exploded to an estimated $2.5 billion by 1995. That led to a business-school bonanza--a 43 percent rise in M.B.A. degrees during the 1990s--that created an entire class of professionals dedicated to management. One University of California-Berkeley business school grad, Scott Adams, even created a cartoon for the working stiff, Dilbert, an engineer who confronts the daily absurdities brought on by trained managers.

Recently, management became personalized in the form of celebrity CEOs. For decades Alfred Sloan, a low-key, country-club type who didn't consort with the workers and managed by interoffice memo, typified the chief executive. By the 1990s, CEOs had become new-age messiahs, spreading a flamboyant gospel of motivation and empowerment that could bring success to all aspects of human enterprise. The personification of the breed: former General Electric CEO Jack Welch. But owing to the bear market and a rash of corporate scandals, "the bold turnaround and the white knight savior have been discredited," says Joseph Badaracco, a Harvard Business School professor and author of Leading Quietly: An Unorthodox Guide to Doing the Right Thing. "It's back-to-basics time for managers," adds Tom Brown, author of The Anatomy of Fire, a book about 21st-century management.

The back-to-basics trend, if indeed it is one, has certainly been on display in recent months at the world's largest media company. After the hype surrounding the two-year-old merger of Time Warner and AOL faded and the promised synergies never arrived, a diplomatic attorney has pushed aside a charismatic Internet visionary and a colorful media tycoon to head the ailing firm. With Steve Case and Ted Turner on the way out, new chairman Dick Parsons has promised fewer big deals and radical transformations and more careful stewardship of assets to reverse the company's nearly $100 billion loss last year. Who knows? If it works at AOL, back to basics may become the next management trend worth a try.