ADVANCES in technology are widely regarded as major sources of improve- ments in the competitive positions of firms and industries as well as of increases in national economic growth rates and standards of living. Because the benefits of such advances obviously depend on the extent to which they are utilized, considerable research has been focused on the diffusion of technological innovations. Most of these studies have sought to measure the dimensions of technological diffusion and to explain differences in diffusion patterns among innovations, industries and nations as well as changes in such patterns over time. As is to be expected during the explora- tory probing of major new problems, however, the most valuable contribu- tions made so far have been to reveal the need for more penetrating concepts, better measures, more comprehensive analytical frameworks and wider samplings of the variegated phenomena to be encompassed. Shortcomings in the theoretical work have seldom been directly harmful to industrial managements because they rely on their own more detailed knowledge of the relevant facts and problems. But such research reports have tended to mislead government officials and scholars concerning the depth and accuracy of our understanding of the causes and effects of differences among, and changes in, observed diffusion patterns. The following paper surveys the literature of the past 20-25 years in this area, and provides a critique of some of its shortcomings