This article presents the central underlying dynamic of "preserve the core/stimulate progress" that enables enduring companies to adapt to and prosper in a changing and difficult world. It is based on a six–year research project (which led to our book Built to Last1), for which we systematically studied the founding, growth, and development of exceptional companies that have stood the test of time, including: Boeing, Disney, General Electric (GE), Hewlett–Packard (HP), Johnson & Johnson, Marriott, Merck, Motorola, Nordstrom, Procter & Gamble, Sony, and 3M. Our "visionary companies" (as we eventually came to call the 18 companies we studied) had both endurance, with an average age of nearly 100 years, and sustained performance, having outperformed the stock market 15 times since 1926. We also studied each visionary company in contrast to a "comparison company" that had roughly the same shot in life, but didn't turn out as well: for example, 3M in contrast to Norton, Procter & Gamble in contrast to Colgate, Motorola in contrast to Zenith, and so on.