Recent changes in the structure of domestic and international economies have led to a wide range of popular accounts of a ‘globalized’ and ‘New Economy.’' Economies of scale are available to everyone with access to the Internet and network externalities seem more important than traditional measures of size. It is far too early, however, to dismiss the importance of large national and multinational corporations and their role in the international political economy. This paper describes and analyzes the world’s fifty largest corporations that not only constitute a tangible portion of global industrial and service capacity but also are among the most politically influential economic actors. Working within the context of previous studies, the paper compares the largest fifty corporations in the world’s market economies in 1955, 1975, and 2000. It presents and analyzes basic and emerging trends, industrial change, and the continued increased importance of high international content distinguishing high-performance firms from others. Past size and success is no guarantee for a spot on the top; change was and maybe even more so still is ubiquitous. The growing importance of the service sector is also manifested in the nature (and output) of many of the firms, as is the growing importance of informational content.