While the world has changed immeasurably, corporate cultures formed in the World War II build-up are intact and operative in aerospace and defense companies today. These cultures have proven impervious to decades of top-down change efforts. Surfacing and rethinking assumptions is recommended as an approach to breaking the change impasse. A three-level model of culture is presented in which assumptions are the foundation component of corporate culture. In order for cultural change to proceed, organizations must use a combination of outsider questions and insider knowledge to surface and inspect these assumptions.