In 1965, when quantitative planning was much in vogue, Royal Dutch Shell started experimenting with a different way of looking into the future: scenario planning. Shell's practice has now survived for almost half a century and has had a huge influence on how businesses, governments, and other organisations think about and plan for the future. To produce this illuminating study, the authors interviewed almost every living veteran of the Shell scenario planning operation, along with top Shell executives through the years. They identify several principles that both define the process at Shell and help explain how it has thrived for so long. For instance, Shell scenarios are stories, not predictions, and are designed to help break the habit, ingrained in most corporate planning, of assuming that the future will look much like the present.