Analyzes how successful firms fail when confronted with technological and market changes, prescribing a list of rules for firms to follow as a solution. Precisely because of their adherence to management principles, innovative, well-managed firms fail at the emergence of disruptive technologies - that is, innovations that disrupt the existing dominant technologies in the market. Unfortunately, it usually does not make sense to invest in disruptive technologies until after they have taken over the market. Thus, instead of exercising what are typically managerial decisions, at the introduction of technical or market change it is very often the case that managers must make counterintuitive decisions not to listen to customers, to invest in lower-performance products that produce lower margins, and to pursue small markets. From analysis of the disk drive industry, a set of rules is devised - the principles of disruptive innovation - for managers to measure when traditional management principles should be followed or rejected. According to the principles of disruptive innovation, a manager should plan to fail early, often, and inexpensively, developing disruptive technologies in small organizations operating within a niche market and with a relevant customer base. A case study in the electric-powered vehicles market illustrates how a manager can overcome the challenges of disruptive technologies using these principles of disruptive innovation. The mechanical excavator industry in the mid-twentieth century is also described, as an example in which most companies failed because they were unwilling to forego cable excavator technology for hydraulics machines. While there is no right answer or formula to use when reacting to unpredictable technological change, managers will be able to adapt as long as they realize that good managerial practices are only situationally appropriate. Though disruptive technologies are inherently high-risk, the more a firm invests in them, the more it learns about the emerging market and the changing needs of consumers, so that incremental advances may lead to industry-changing leaps. (CJC)