What are the levers behind the performance of a specific firm? Many possible answers might come to the reader s mind: strategy, financial situation, marketing capabilities in two words: competitive advantage.This book tries to include Organizational Capability into the equation of company performance. The starting point is the definition of competitive advantage by D. Ulrich; from this cornerstone, I try to develop a comprehensive framework to capture the presence of Organizational Capability in a company and to assess its impact on the firm s specific competitive advantage.The aim is not to create the ultimate solution to the problem of measuring the reasons behind competitive advantage but to create a starting point to foster the further debate and development of more far-reaching models.