Does ambush marketing work? and if it does, is it better than official sponsorship? This book analyzes the phenomenon of ambush marketing and it investigates its causes and consequences from a managerial perspective. The evolution of this competitive tool has brought marketers to the point that they must deal with it during every major sports event and try to cope with it. This analysis makes you understand how ambush marketing has gotten to then point that it is not just a counter strategy to official sponsorship, but it can also be what a company needs in order to pursue a desired positioning. By going through the history and interviewing three top managers of two of the biggest actors and in the sports apparel industry, we try to highlight what makes them choose either side of the sponsorship field. We define advantages and disadvantages of each perspective and assess the effect of ambush-marketing practices on consumer by analyzing the result of an actual survey conducted during a match of the 2010 RBS 6 NAtions tournament.