Y Combinator is the investment firm that pioneered the current Silicon Valley vogue for investing seed money ($18,000 on average) in nascent startups and then helping them turn their ideas into companies. The partners, all successful entrepreneurs, offer individualized attention during a three-month program held each winter and summer in Mountain View, California. But the secret of YC's success—more than 25 of its grads have been acquired and the firm has fostered breakout stars such as Airbnb and Dropbox—is its network. "One of the loneliest things in the world is starting and running a company," says YC alum Matt Brezina, who went through the program in 2006. "YC puts a bunch of like-minded people together to support each other."
"The closest thing before was the PayPal mafia," says cofounder Paul Graham. "That was 15 or 20 people. Before the last [class], the Y Combinator network was 672 people." The tight-knit community is forged through weekly dinners attended by the founders in a particular season's class, where they show their progress, seek advice from each other and YC alums, and question guest speakers such as Mark Zuckerberg. Membership has its perks: 100% of YC companies leave the program with additional financing to build their businesses, thanks to a deal with star investors Ron Conway and Yuri Milner, who offer $150,000 to any graduate.
Fast Company interviewed dozens of alumni about the relationships they built through YC. The result, seen in this highly edited collection, is what Graham's wife (and YC partner), Jessica Livingston, calls "a supercondensed version of Silicon Valley."
Infographic by Liz Meyer