Bob Dorf, a serial entrepreneur, is often called the “midwife of Customer Development,” helping Steve Blank deploy it when Blank’s eighth start-up, E.piphany, opened in 1996. The two have been friends and colleagues since. Dorf is co-author with Steve Blank of The Start-up Owner’s Manual. He also runs the firm’s boutique consultancy, helping major corporations and start-ups alike effectively deploy the Customer Development process. Entrepreneurial since age 12, Dorf founded six companies, most explosive of which was Marketing 1to1 (later Peppers & Rogers Group), a former Inc. 500 company. He's invested in or advised more than a score of start-ups and teaches Customer Development at Columbia Business School.