Teams using XP are guided by the XP Values through their use of the XP Practices. The XP Practices are each best practices, but the practices also leverage the benefits of the other practices to form an efficient, minimal set of practices required to deliver high quality software aligned to customer needs.

In general, teams will be most effective in their use of XP if each of the practices is used as much as possible on the project. In practice, this can be difficult to achieve for a number of reasons, including:

• Technical obstacles, such as non-OO languages and legacy code
• Lack of skills, including basic programming skills, practice skills, domain expertise, teamwork skills
• A complex customer environment, where a single source of prioritized stories is difficult to develop
• Organizational obstacles, such as distributed teams, large teams, and command/control oriented cultures

As the team uses XP, these obstacles affect their ability to effectively use the practices. The XP Coach helps the team address how these challenges will affect their use of the practices. This starts with helping the team maintain the Courage to confront and remove these obstacles, clearing the way for the practices to be used. In cases where the obstacles cannot be removed, the coach and the team use the XP Values to guide adaptation of the practices.

The XP Coach needs to participate in communities that share best practices in software development and XP. These communities will exist within large companies, in local users groups, and in Internet communities.