Good to Great: Why Some Companies Make the Leap... and Others Don't is a management book by Jim C. Collins that describes how companies transition from being good companies to great companies, and how most companies fail to make the transition. The book (buy on Amazon) was a bestseller, selling four million copies and going far beyond the traditional audience of business books. Collins identified several key characteristics in companies that made the leap from good to great. Collins found that the main reason certain companies become great is they narrowly focus the company’s resources on their field of key competence.