This paper presents the Extreme Software Development (XP) Metaphor Evaluation and Architecture. It provides a straightforward, semiotics-based structural model of system metaphors that provides a fundamental account of how metaphors may bring value to a software system. It identifies activities that teams can use to construct metaphors for their systems as well as evaluation techniques for system metaphors. This results will reassure Extreme Programming teams to carry on using system metaphors to reinforce their growth practices, rather than abandoning them.