Inc. is now accepting entries for its annual lists of fastest-growing private U.S. companies. The top 500 companies are covered in the September issue of the magazine, and 5,000 companies are profiled on This year, a new ranking will determine which small businesses have generated the most jobs.

"The 2009 list will be the most important we've ever published," says John Koten, CEO and Editor-in-Chief of Mansueto Ventures, Inc.'s parent company. Koten says that the job creation ranking is meant to support the Obama administration's focus on employment: "This is a way we can help to support this vital cause."

Inc.'s ranking orders companies by percentage of growth over a three year period, which for this year began on January 7, 2005. Other rankings draw on categories like industries (energy, IT services, transportation), as well as by revenue. The list is also broken down to recognize the fast-growing companies at the state and local level.

To qualify for the Inc. 500|5000 list, companies must be private, U.S.-based, for profit, independent and earning revenue since January 7, 2005 or earlier. Companies that wish to be considered should apply at, before the deadline of March 31, 2009.

Last year's No. 1 company was Senior Whole Health of Cambridge, Massachusetts, which grew by more than 30,000 percent thanks to a commitment to a new kind of health plan that streamlines Medicare and Medicaid for special-needs customers.

Notable previous winners include Microsoft, Intel, Intuit, Qualcomm and Kingston Technology.

The list is not only a ranking, but a database that is intended to be used to advance the study of company growth and the entrepreneurial economy in the United States.

Past research based on the Inc. 500 includes a study of the personality types of Inc. 500 company founders and CEOs, and a study of Inc. 500 companies that sought to determine if there is a correlation between high growth and profitability. A recent study by the University of Massachusetts, Dartmouth, measured the use of social media by Inc. 500 companies.

The Inc. 500|5000 focuses on an important group of U.S. employers—high growth companies. According to a recent study by the U.S. Census Bureau, without start-ups, the United States would have had a net loss in jobs between 1980 and 2005. "It's really only a sub segment of the small business economy—growth-oriented new firms—that is responsible for job creation," says Koten.