Before the days of the Internet, it was primarily venture capitalists who coached young entrepreneurs in Silicon Valley. Today, because of the phenomenal number of new companies, venture capitalists are just too busy. The largest firms still take on a few carefully selected, highly promising zero-stage start-ups, but they simply can't spend the time on ones that aren't going to grow huge quickly. To fill the void, a new breed of adviser has stepped in to coach entrepreneurs. Called mentor capitalists, they help entrepreneurs with everything from recruiting top talent to attracting their first million in seed money. The mentor capitalists in Silicon Valley are cashed-out, highly successful business architects who no longer want to start businesses but who love the thrill of the entrepreneurial game. They spend hours and hours with first-time entrepreneurs, guiding them as they create and refine a business model, test their ideas in the marketplace, build business processes, raise money, and find talent. The authors of this article found through dozens of extensive interviews with entrepreneurs and their coaches that mentor capitalists play many roles: sculptor, psychologist, diplomat, kingmaker, talent magnet, process engineer, and rainmaker. In exchange for small equity stakes, the mentor capitalists wear these different hats, doling out expertise just in time, as situations arise, and in doses appropriate to the situation. Mentor capitalists seed Silicon Valley with expertise and knowledge, augmenting or even substituting for classes in entrepreneurship at local universities. But, as the authors note, the role of the mentor capitalist is essential to any start-up, anywhere.