In the early 2010s, the telecom world readied itself to roll out 4G, the latest generation in mobile networks. At Swedish telecom giant Ericsson, management realized that developing the next 5G mobile networks would require a speed and organizational flexibility that was beyond what the company could master. And so, in 2011, it set out to change itself from a Waterfall to a Lean and Agile organization.Marianne Rimbark was at the core of this transformation. As project manager, and later program manager for Digital Transformation, the change processes that she initiated would come to involve 550 different teams and 14,500 people across the globe. This isn t just a large transformation, it is an XXL transformation, she wrote in the blog she kept during the five years that the transformation played out. Her blog became the basis for this book. A story told from the day-to-day lives at Ericsson and as such, a contribution to the global Lean and Agile community.