Extreme programming (XP) is one of the well-known forms of agile software development, due to its iterative nature, software developers focus on functional aspects and neglect the non-functional characteristics of software like usability. This research investigates the importance of end user involvement in extreme programming using grounded theory and describes the key question that how usability practices are integrated with the Extreme Programming in orders to make effective usable software system. To address this key issue, this study provide an extension suggestion for extreme programming that help the development team to take an account of usability of the product. While there are many usability engineering techniques, discount usability (Scenarios, Card Sorting, Heuristic evaluation and thinking aloud) that are applied with a minimum set of guidance and tools were integrated into extreme programming project lifecycle.