<p>In this paper we explore the relationship between computers and productivity growth at the firm level. We apply standard productivity and growth accounting techniques to data from 600 large US firms over 1987-1994. While we find that computer make a positive and significant contribution to output growth in the short term (using 1 year differences), the implied returns to computers are two to five times greater when differences are taken over seven years instead of one year. Our results challenge the conclusions drawn from aggregate data on computers and productivity, but are consistent with case evidence that the combination of computers and organizational co-investments make a substantial contribution to growth</p>