He is 48 years old. He founded the company 12 years ago. Today he holds 21% of the equity, plus the lion's share of the responsibility. His picture prefaces the company's annual report. He is the chief executive officer of one of America's 100 fastest-growing public companies as determined by INC. in May 1983.

He trained as an engineer. Frustrated by bureaucracy and paperwork when he was at a Fortune 500 company, he saw a market niche and went after it on his own. Hampered by insufficient capital at the launch, he lived for the job -- and made the business grow. The company he founded in the early 1970s with a handful of employees now has 683 names on the payroll and sales of $53 million a year.

The business has made him wealthy, but the satisfaction no longer comes from cash. Now it comes with the constantly changing challenges. He still works a 60-hour week and vows he will never retire.

And he doesn't exist, except in statistics. There is no "average" CEO of the INC. 100 companies; instead there are 100 distinct individuals -- 97 men and three women, as diverse as the companies they head. They include 20 providers of health-care products and services, 17 computer manufacturers, 11 energy producers, eight data processor manufacturers, and five restaurateurs and the heads of four cable television systems and three word processing companies. There are equipment lessors, a fashion designer, and a diet king. Frank Lasater, of Flare Inc., the youngest CEO on the list, is 32. George Acker, of Cable TV Industries, the oldest, is 71. John Sculley, brought over from giant PepsiCo, has been CEO at Apple Computer Inc. for only a few months, while Konrad Ruckstuhl, founder and CEO of SPM Group, has been with his business for 44 years. But they all share the satisfaction, and the solitary pressures, that go with the title of CEO.

The idea of drawing a composite portrait of the INC 100 CEO began with a shattered assumption. According to conventional wisdom, the entrepreneur and the manager are two different types. The skills necessary to launch a new company, so the myth holds, are radically different from those needed to run it smoothly once it has crossed a certain threshold -- $10 million, say, or $50 million.

The INC. 100 report disproved the myth. Of the small companies represented, 76 are still managed by their founders Since the report was published, we have looked closer at the 100 CEOs, entrepreneurial founder and hired manager alike, persuading some two-thirds to participate in hour-long interviews. The result is an insider's answer to who is running America's fastest-growing companies.