A longitudinal case study evaluating the effects of adopting the Extreme Programming (XP) methodology was performed at Sabre Airline Solutions™. The Sabre team was a characteristically agile team in that they had no need to scale or re-scope XP for their project parameters and organizational environment. The case study compares two releases of the same product. One release was completed just prior to the team's adoption of the XP methodology, and the other was completed after approximately two years of XP use. Comparisons of the new release project results to the old release project results show a 50% increase in productivity, a 65% improvement in pre-release quality, and a 35% improvement in post-release quality. These findings suggest that, over time, adopting the XP process can result in increased productivity and quality.