Mastering change is crucial to your success as a technology organization. It creates the most risk and opportunity in any environment. Change comes from new service implementation, new technology adoption, network expansion, software updates, or a thousand other ways. It is inherent to data center convergence, enterprise expansion, and new service deployments that require you to combine many different technologies—including physical and virtualized devices—into a single network infrastructure. Such networks must handle massive amounts of traffic, while delivering the quality of experience that mission critical applications demand. To succeed during times of change you need to measure where you are, what the change will bring, and the success of the outcome. This paper will focus on how testing helps you manage change to have more successful projects, roll-outs, and updates.