One of the steepest challenges a strategist faces is to navigate his or her company through a period of industry transformation--an era of rapid and wholesale changes in industry structure. This note considers how periods of transformation typically unfold. It then examines how the core tools of the strategist can be deployed during such periods and how new tools come to the fore. Periods of industry transformation pose grave threats and tremendous opportunities to companies. Industry leaders are often unseated during such times, replaced by underdogs and entrants. Perhaps most importantly, periods of transformation give companies unusual latitude to influence future industry structure. Teaching purpose: Designed to support course modules that consider strategy-making under uncertainty or the intersection of competitive strategy and technology.