Why is it that business in Silicon Valley is again flourishing while along Route 128 in Massachusetts it continues to decline? The answer, Sexanian suggests, has to do with the fact that despite similar histories and technologies, Silicon Valley developed a decentralized but co-operative industrial system while Route 128 came to be dominated by independent, self-sufficient corporations. The result of more than 100 interviews, this analysis highlights the importance of local sources of competitive advantage in a volatile world economy.