We've all heard the pitch from professional investors, "Sure you can grow on your own -- but you can grow a lot faster with our money." Makes sense right? To grow fast, you need growth capital, often more than the business can generate internally. So we were surprised to learn that of the top nine breakthrough companies identified in our study, not one of them was financed during the startup stage by professional investors (Scott Cook of Intuit accepted a small amount of venture capital right before he went public -- but that was mainly to get famed VCs John Doerr and Burt McMurtry on his board).

That's right, the nine Inc. companies in our study that increased revenue and profits the fastest over a 22-year period started out with friends and family money -- and financed themselves internally well into maturity. Not that outside capital is bad. In our fieldwork with 52 companies over a five-year period, we came across a number of examples of how the right financial partner at the right time can make a real difference in a company's growth trajectory. But you should accept outside capital when and if it makes sense to you -- and not because someone tells you that it is a necessary requirement for success. Our research suggests it isn't.