Soccer coaches must understand the principles of play if they want to succeed. The principles of play are the rules of action that support the basic objectives of soccer and the foundation of a soccer coaching strategy. They serve as a set of permanent criteria that coaches can use to evaluate the efforts of their team. In this article, the author describes the five attacking and five defending principles of play, but before players begin to understand the attacking and defending principles of play, each must understand the two objectives of play--attacking and defending. He recommends the five attacking and five defending principles of play to be practiced by all soccer coaches at every training session and at every match.