A transition to an agile software development methodology in a heavily waterfall-oriented organization is discussed. A collection of agile software development practices implemented at Sabre Holdings is described. A summary of the desired set of practices is given, along with data summarizing the degree of pervasiveness of these practices in real life. Quantitative results on the use of the methodology in day-to-day development are presented. Lessons learned and mitigation ideas are also discussed. The gathered information shows that the habits of the old model can strongly encumber the implementation of an agile methodology, but even implementation of a few practices yields very tangible results.